build(deps-dev): bump parallel_tests from 5.5.0 to 5.6.0 (#4836)

Bumps [parallel_tests](https://github.com/grosser/parallel_tests) from 5.5.0 to 5.6.0.
- [Changelog](https://github.com/grosser/parallel_tests/blob/master/CHANGELOG.md)
- [Commits](grosser/parallel_tests@v5.5.0...v5.6.0)

---
updated-dependencies:
- dependency-name: parallel_tests
  dependency-version: 5.6.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -351,7 +351,7 @@ GEM
     ostruct (0.6.3)
     palm_civet (1.1.0)
     parallel (1.27.0)
-    parallel_tests (5.5.0)
+    parallel_tests (5.6.0)
       parallel
     parser (3.3.10.1)
       ast (~> 2.4.1)