Bump rexml from 3.3.6 to 3.3.7 (#492)

Bumps [rexml](https://github.com/ruby/rexml) from 3.3.6 to 3.3.7.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.3.6...v3.3.7)

---
updated-dependencies:
- dependency-name: rexml
  dependency-type: indirect
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -44,8 +44,7 @@ GEM
     rainbow (3.1.1)
     rake (13.2.1)
     regexp_parser (2.9.2)
-    rexml (3.3.6)
-      strscan
+    rexml (3.3.7)
     rspec (3.13.0)
       rspec-core (~> 3.13.0)
       rspec-expectations (~> 3.13.0)
@@ -89,7 +88,6 @@ GEM
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.12.3)
     simplecov_json_formatter (0.1.4)
-    strscan (3.1.0)
     unicode-display_width (2.6.0)
     uri (0.13.0)
     yard (0.9.37)