Build(deps-dev): Bump rails-dom-testing from 2.1.1 to 2.2.0

Bumps [rails-dom-testing](https://github.com/rails/rails-dom-testing) from 2.1.1 to 2.2.0.
- [Release notes](https://github.com/rails/rails-dom-testing/releases)
- [Commits](rails/rails-dom-testing@v2.1.1...v2.2.0)

---
updated-dependencies:
- dependency-name: rails-dom-testing
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -441,7 +441,7 @@ GEM
       rack
     rack-test (2.1.0)
       rack (>= 1.3)
-    rails-dom-testing (2.1.1)
+    rails-dom-testing (2.2.0)
       activesupport (>= 5.0.0)
       minitest
       nokogiri (>= 1.6)