Update symfony/var-dumper requirement from ^6.3 to ^6.3 || ^7.0

Updates the requirements on [symfony/var-dumper](https://github.com/symfony/var-dumper) to permit the latest version.
- [Release notes](https://github.com/symfony/var-dumper/releases)
- [Changelog](https://github.com/symfony/var-dumper/blob/7.0/CHANGELOG.md)
- [Commits](symfony/var-dumper@v6.3.0...v7.0.0)

---
updated-dependencies:
- dependency-name: symfony/var-dumper
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

composer.json

@@ -35,7 +35,7 @@
         "phpstan/phpstan-strict-rules": "^1.5",
         "phpunit/phpunit": "^10.4",
         "roave/security-advisories": "dev-latest",
-        "symfony/var-dumper": "^6.3"
+        "symfony/var-dumper": "^6.3 || ^7.0"
     },
     "autoload": {
         "psr-4": {