Bump rubocop-rails from 2.15.1 to 2.15.2

Bumps [rubocop-rails](https://github.com/rubocop/rubocop-rails) from 2.15.1 to 2.15.2.
- [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/v2.15.1...v2.15.2)

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

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

Gemfile.lock

@@ -112,6 +112,7 @@ GEM
     jbuilder (2.11.5)
       actionview (>= 5.0.0)
       activesupport (>= 5.0.0)
+    json (2.6.2)
     loofah (2.18.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
@@ -122,7 +123,7 @@ GEM
     method_source (1.0.0)
     mini_magick (4.11.0)
     mini_mime (1.1.2)
-    minitest (5.16.1)
+    minitest (5.16.2)
     msgpack (1.5.2)
     net-imap (0.2.3)
       digest
@@ -153,7 +154,7 @@ GEM
     puma (5.6.4)
       nio4r (~> 2.0)
     racc (1.6.0)
-    rack (2.2.3.1)
+    rack (2.2.4)
     rack-mini-profiler (3.0.0)
       rack (>= 1.2.0)
     rack-test (1.1.0)
@@ -208,7 +209,8 @@ GEM
       rspec-mocks (~> 3.10)
       rspec-support (~> 3.10)
     rspec-support (3.11.0)
-    rubocop (1.30.1)
+    rubocop (1.31.1)
+      json (~> 2.3)
       parallel (~> 1.10)
       parser (>= 3.1.0.0)
       rainbow (>= 2.2.2, < 4.0)
@@ -219,7 +221,7 @@ GEM
       unicode-display_width (>= 1.4.0, < 3.0)
     rubocop-ast (1.18.0)
       parser (>= 3.1.1.0)
-    rubocop-rails (2.15.1)
+    rubocop-rails (2.15.2)
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 1.7.0, < 2.0)