Bump rubocop-rails from 2.15.0 to 2.15.1

Bumps [rubocop-rails](https://github.com/rubocop/rubocop-rails) from 2.15.0 to 2.15.1.
- [Release notes](https://github.com/rubocop/rubocop-rails/releases)
- [Changelog](https://github.com/rubocop/rubocop-rails/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop/rubocop-rails/compare/v2.15.0...v2.15.1)

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

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

Gemfile.lock

@@ -238,7 +238,7 @@ GEM
     mini_magick (4.11.0)
     mini_mime (1.1.2)
     mini_portile2 (2.8.0)
-    minitest (5.16.0)
+    minitest (5.16.1)
     minitest-autotest (1.1.1)
       minitest-server (~> 1.0)
       path_expander (~> 1.0)
@@ -405,7 +405,7 @@ GEM
     rubocop-performance (1.14.2)
       rubocop (>= 1.7.0, < 2.0)
       rubocop-ast (>= 0.4.0)
-    rubocop-rails (2.15.0)
+    rubocop-rails (2.15.1)
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 1.7.0, < 2.0)
@@ -492,7 +492,7 @@ GEM
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.8.2)
-    unicode-display_width (2.1.0)
+    unicode-display_width (2.2.0)
     uri_template (0.7.0)
     web-console (4.2.0)
       actionview (>= 6.0.0)