Bump shoulda-matchers from 5.3.0 to 6.0.0 (#2476)

Bumps [shoulda-matchers](https://github.com/thoughtbot/shoulda-matchers) from 5.3.0 to 6.0.0.
- [Release notes](https://github.com/thoughtbot/shoulda-matchers/releases)
- [Changelog](https://github.com/thoughtbot/shoulda-matchers/blob/main/CHANGELOG.md)
- [Commits](thoughtbot/shoulda-matchers@v5.3.0...v6.0.0)

---
updated-dependencies:
- dependency-name: shoulda-matchers
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Gemfile.lock

@@ -298,7 +298,7 @@ GEM
       websocket (~> 1.0)
     sentry-raven (3.1.2)
       faraday (>= 1.0)
-    shoulda-matchers (5.3.0)
+    shoulda-matchers (6.0.0)
       activesupport (>= 5.2.0)
     smart_properties (1.17.0)
     sprockets (4.2.0)