Bump rubocop-rails from 2.15.2 to 2.21.2

Bumps [rubocop-rails](https://github.com/rubocop/rubocop-rails) from 2.15.2 to 2.21.2.
- [Release notes](https://github.com/rubocop/rubocop-rails/releases)
- [Changelog](https://github.com/rubocop/rubocop-rails/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop-rails@v2.15.2...v2.21.2)

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

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -99,7 +99,7 @@ GEM
     coffee-script-source (1.12.2)
     composite_primary_keys (11.3.1)
       activerecord (~> 5.2.4)
-    concurrent-ruby (1.1.10)
+    concurrent-ruby (1.2.2)
     connection_pool (2.2.5)
     crack (0.4.5)
       rexml
@@ -278,7 +278,7 @@ GEM
     http_accept_language (2.1.1)
     http_parser.rb (0.6.0)
     httpclient (2.8.3)
-    i18n (1.12.0)
+    i18n (1.14.1)
       concurrent-ruby (~> 1.0)
     i18n-js (3.8.0)
       i18n (>= 0.6.6)
@@ -300,7 +300,7 @@ GEM
       rails-dom-testing (>= 1, < 3)
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
-    json (2.6.2)
+    json (2.6.3)
     json_expressions (0.9.0)
     jwt (2.5.0)
     launchy (2.5.0)
@@ -340,7 +340,7 @@ GEM
       rake
     mini_mime (1.1.2)
     mini_portile2 (2.8.0)
-    minitest (5.16.3)
+    minitest (5.20.0)
     minitest-reporters (1.5.0)
       ansi
       builder
@@ -404,9 +404,10 @@ GEM
       mime-types
       mimemagic (~> 0.3.0)
       terrapin (~> 0.6.0)
-    parallel (1.22.1)
-    parser (3.1.2.1)
+    parallel (1.23.0)
+    parser (3.2.2.4)
       ast (~> 2.4.1)
+      racc
     passenger (6.0.14)
       rack
       rake (>= 0.8.1)
@@ -422,7 +423,7 @@ GEM
     puma (5.6.5)
       nio4r (~> 2.0)
     racc (1.6.0)
-    rack (2.2.4)
+    rack (2.2.8)
     rack-accept (0.4.5)
       rack (>= 0.4)
     rack-cors (1.1.1)
@@ -486,7 +487,7 @@ GEM
     redis (4.8.0)
     redis-namespace (1.9.0)
       redis (>= 4)
-    regexp_parser (2.6.0)
+    regexp_parser (2.8.2)
     representable (3.2.0)
       declarative (< 0.1.0)
       trailblazer-option (>= 0.1.1, < 0.2.0)
@@ -509,7 +510,7 @@ GEM
     retriable (3.1.2)
     reverse_markdown (1.1.0)
       nokogiri
-    rexml (3.2.5)
+    rexml (3.2.6)
     rspec (3.11.0)
       rspec-core (~> 3.11.0)
       rspec-expectations (~> 3.11.0)
@@ -533,19 +534,19 @@ GEM
       rubocop-ast (>= 1.19.1, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.23.0)
-      parser (>= 3.1.1.0)
+    rubocop-ast (1.29.0)
+      parser (>= 3.2.1.0)
     rubocop-performance (1.15.0)
       rubocop (>= 1.7.0, < 2.0)
       rubocop-ast (>= 0.4.0)
-    rubocop-rails (2.15.2)
+    rubocop-rails (2.21.2)
       activesupport (>= 4.2.0)
       rack (>= 1.1)
-      rubocop (>= 1.7.0, < 2.0)
+      rubocop (>= 1.33.0, < 2.0)
     rubocop-rake (0.6.0)
       rubocop (~> 1.0)
     ruby-openid (2.9.2)
-    ruby-progressbar (1.11.0)
+    ruby-progressbar (1.13.0)
     ruby2_keywords (0.0.5)
     rubyzip (2.3.2)
     sanitize (5.2.3)
@@ -642,13 +643,13 @@ GEM
       multipart-post (~> 2.0)
       naught (~> 1.0)
       simple_oauth (~> 0.3.0)
-    tzinfo (1.2.10)
+    tzinfo (1.2.11)
       thread_safe (~> 0.1)
     uber (0.1.0)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.7)
-    unicode-display_width (2.3.0)
+    unicode-display_width (2.5.0)
     web-console (3.7.0)
       actionview (>= 5.0)
       activemodel (>= 5.0)