Bump the test-dependencies group with 1 update (heroku#709)

Bumps the test-dependencies group with 1 update: [parallel_tests](https://github.com/grosser/parallel_tests).


Updates `parallel_tests` from 4.5.1 to 4.6.0
- [Changelog](https://github.com/grosser/parallel_tests/blob/master/CHANGELOG.md)
- [Commits](grosser/parallel_tests@v4.5.1...v4.6.0)

---
updated-dependencies:
- dependency-name: parallel_tests
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: test-dependencies
...

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

Gemfile.lock

@@ -26,7 +26,7 @@ GEM
     moneta (1.0.0)
     multi_json (1.15.0)
     parallel (1.24.0)
-    parallel_tests (4.5.1)
+    parallel_tests (4.6.0)
       parallel
     platform-api (3.6.0)
       heroics (~> 0.1.1)