composer(deps-dev): Update phpunit/phpunit requirement from 9.6.20 to…

… 9.6.21 (#197)

Updates the requirements on
[phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) to
permit the latest version.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/sebastianbergmann/phpunit/releases">phpunit/phpunit's
releases</a>.</em></p>
<blockquote>
<h2>PHPUnit 9.6.21</h2>
<h3>Changed</h3>
<ul>
<li><a
href="https://redirect.github.com/sebastianbergmann/phpunit/issues/5956">#5956</a>:
Deprecation of the <code>E_STRICT</code> constant in PHP 8.4</li>
<li>Removed <code>.phpstorm.meta.php</code> file as methods such as
<code>TestCase::createStub()</code> use generics / template types for
their return types and PhpStorm, for example, uses that information</li>
</ul>
<hr />
<p><a href="https://docs.phpunit.de/en/9.6/installation.html">How to
install or update PHPUnit</a></p>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/sebastianbergmann/phpunit/blob/9.6.21/ChangeLog-9.6.md">phpunit/phpunit's
changelog</a>.</em></p>
<blockquote>
<h2>[9.6.21] - 2024-09-19</h2>
<h3>Changed</h3>
<ul>
<li><a
href="https://redirect.github.com/sebastianbergmann/phpunit/issues/5956">#5956</a>:
Deprecation of the <code>E_STRICT</code> constant in PHP 8.4</li>
<li>Removed <code>.phpstorm.meta.php</code> file as methods such as
<code>TestCase::createStub()</code> use generics / template types for
their return types and PhpStorm, for example, uses that information</li>
</ul>
<h2>[9.6.20] - 2024-07-10</h2>
<h3>Changed</h3>
<ul>
<li>Updated dependencies (so that users that install using Composer's
<code>--prefer-lowest</code> CLI option also get recent versions)</li>
</ul>
<h2>[9.6.19] - 2024-04-05</h2>
<h3>Changed</h3>
<ul>
<li>The namespaces of dependencies are now prefixed with
<code>PHPUnitPHAR</code> instead of just <code>PHPUnit</code> for the
PHAR distribution of PHPUnit</li>
</ul>
<h2>[9.6.18] - 2024-03-21</h2>
<h3>Changed</h3>
<ul>
<li><a
href="https://redirect.github.com/sebastianbergmann/phpunit/issues/5763">#5763</a>:
Release nullable type changes for PHPUnit 9.6</li>
</ul>
<h2>[9.6.17] - 2024-02-23</h2>
<h3>Changed</h3>
<ul>
<li>Improve output of <code>--check-version</code> CLI option</li>
<li>Improve description of <code>--check-version</code> CLI option</li>
<li>Show help for <code>--manifest</code>, <code>--sbom</code>, and
<code>--composer-lock</code> when the PHAR is used</li>
</ul>
<h3>Fixed</h3>
<ul>
<li><a
href="https://redirect.github.com/sebastianbergmann/phpunit/issues/5712">#5712</a>:
Update dependencies for PHAR distribution of PHPUnit 9.6</li>
</ul>
<h2>[9.6.16] - 2024-01-19</h2>
<h3>Changed</h3>
<ul>
<li>Make PHAR build reproducible (the only remaining differences were in
the timestamps for the files in the PHAR)</li>
</ul>
<h3>Fixed</h3>
<ul>
<li><a
href="https://redirect.github.com/sebastianbergmann/phpunit/issues/5516">#5516</a>:
Assertions that use the <code>LogicalNot</code> constraint
(<code>assertNotEquals()</code>,
<code>assertStringNotContainsString()</code>, ...) can generate
confusing failure messages</li>
<li><a
href="https://redirect.github.com/sebastianbergmann/phpunit/issues/5666">#5666</a>:
<code>--no-extensions</code> CLI option does not work</li>
<li><a
href="https://redirect.github.com/sebastianbergmann/phpunit/issues/5673">#5673</a>:
Confusing error message when migration of a configuration is requested
that does not need to be migrated</li>
</ul>
<h2>[9.6.15] - 2023-12-01</h2>
<!-- raw HTML omitted -->
</blockquote>
<p>... (truncated)</p>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/de6abf3b6f8dd955fac3caad3af7a9504e8c2ffa"><code>de6abf3</code></a>
Prepare release</li>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/2799e420c480dc3451c4e39c650ce4357c708386"><code>2799e42</code></a>
Merge branch '8.5' into 9.6</li>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/48ed828b72c35b38cdddcd9059339734cb06b3a7"><code>48ed828</code></a>
Prepare release</li>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/bc0b86cf861901c60c8a7e62aa0b17f3260d3640"><code>bc0b86c</code></a>
Merge branch '8.5' into 9.6</li>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/d7d8e73cfc78788ff6c77575e2e7657401282bf2"><code>d7d8e73</code></a>
Closes <a
href="https://redirect.github.com/sebastianbergmann/phpunit/issues/5956">#5956</a></li>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/17f4f136331dd04e8fedb602aae119654d5e9481"><code>17f4f13</code></a>
Merge branch '8.5' into 9.6</li>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/90098622cb92f3bec18fe2c25901db6cfeabf2da"><code>9009862</code></a>
Update tools</li>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/ea71f89be82e7fa940ee0bb9500722a6dfafeb71"><code>ea71f89</code></a>
Merge branch '8.5' into 9.6</li>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/e16d525215b66c30eeb94b117462e4c87ebe80f7"><code>e16d525</code></a>
Set COMPOSER_ROOT_VERSION to X.Y.x-dev instead of X.Y-dev</li>
<li><a
href="https://github.com/sebastianbergmann/phpunit/commit/e6a204cd0360ecdb88c200384133df8573abcdb5"><code>e6a204c</code></a>
Merge branch '8.5' into 9.6</li>
<li>Additional commits viewable in <a
href="https://github.com/sebastianbergmann/phpunit/compare/9.6.20...9.6.21">compare
view</a></li>
</ul>
</details>
<br />

<details>
<summary>Most Recent Ignore Conditions Applied to This Pull
Request</summary>

| Dependency Name | Ignore Conditions |
| --- | --- |
| phpunit/phpunit | [>= 11.a, < 12] |
| phpunit/phpunit | [>= 10.a, < 11] |
</details>


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composer.json

@@ -32,7 +32,7 @@
     },
     "require-dev": {
         "ext-json": "*",
-        "phpunit/phpunit": "9.6.20",
+        "phpunit/phpunit": "9.6.21",
         "roave/security-advisories": "dev-latest"
     },
     "prefer-stable": true,