Bump rubocop-rails from 2.11.3 to 2.12.2

Bumps [rubocop-rails](https://github.com/rubocop/rubocop-rails) from 2.11.3 to 2.12.2.
- [Release notes](https://github.com/rubocop/rubocop-rails/releases)
- [Changelog](https://github.com/rubocop/rubocop-rails/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop-rails@v2.11.3...v2.12.2)

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

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

Gemfile.lock

@@ -400,7 +400,7 @@ GEM
       unicode-display_width (>= 1.4.0, < 3.0)
     rubocop-ast (1.11.0)
       parser (>= 3.0.1.1)
-    rubocop-rails (2.11.3)
+    rubocop-rails (2.12.2)
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 1.7.0, < 2.0)
@@ -468,7 +468,7 @@ GEM
       concurrent-ruby (~> 1.0)
     uglifier (4.2.0)
       execjs (>= 0.3.0, < 3)
-    unicode-display_width (2.0.0)
+    unicode-display_width (2.1.0)
     websocket-driver (0.7.5)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)