Add Gemfile.lock to version control

Related to removing version constraints in 286944a,

Running locked version of these in CI will help avoid unexpected
failures for unrelated changes.

.gitignore

@@ -12,8 +12,6 @@ test/tmp
 test/version_tmp
 tmp
 
-Gemfile.lock
-
 # YARD artifacts
 .yardoc
 _yardoc

Gemfile.lock

@@ -0,0 +1,84 @@
+PATH
+  remote: .
+  specs:
+    rubocop-github (0.16.2)
+      rubocop
+      rubocop-performance
+      rubocop-rails
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    actionview (5.2.6)
+      activesupport (= 5.2.6)
+      builder (~> 3.1)
+      erubi (~> 1.4)
+      rails-dom-testing (~> 2.0)
+      rails-html-sanitizer (~> 1.0, >= 1.0.3)
+    activesupport (5.2.6)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (>= 0.7, < 2)
+      minitest (~> 5.1)
+      tzinfo (~> 1.1)
+    ast (2.4.2)
+    builder (3.2.4)
+    concurrent-ruby (1.1.9)
+    crass (1.0.6)
+    erubi (1.10.0)
+    i18n (1.8.11)
+      concurrent-ruby (~> 1.0)
+    loofah (2.13.0)
+      crass (~> 1.0.2)
+      nokogiri (>= 1.5.9)
+    minitest (5.15.0)
+    nokogiri (1.13.1-x86_64-darwin)
+      racc (~> 1.4)
+    parallel (1.21.0)
+    parser (3.1.0.0)
+      ast (~> 2.4.1)
+    racc (1.6.0)
+    rack (2.2.3)
+    rails-dom-testing (2.0.3)
+      activesupport (>= 4.2.0)
+      nokogiri (>= 1.6)
+    rails-html-sanitizer (1.4.2)
+      loofah (~> 2.3)
+    rainbow (3.1.1)
+    rake (12.3.3)
+    regexp_parser (2.2.0)
+    rexml (3.2.5)
+    rubocop (1.24.1)
+      parallel (~> 1.10)
+      parser (>= 3.0.0.0)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
+      rexml
+      rubocop-ast (>= 1.15.1, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 1.4.0, < 3.0)
+    rubocop-ast (1.15.1)
+      parser (>= 3.0.1.1)
+    rubocop-performance (1.13.1)
+      rubocop (>= 1.7.0, < 2.0)
+      rubocop-ast (>= 0.4.0)
+    rubocop-rails (2.13.1)
+      activesupport (>= 4.2.0)
+      rack (>= 1.1)
+      rubocop (>= 1.7.0, < 2.0)
+    ruby-progressbar (1.11.0)
+    thread_safe (0.3.6)
+    tzinfo (1.2.9)
+      thread_safe (~> 0.1)
+    unicode-display_width (2.1.0)
+
+PLATFORMS
+  x86_64-darwin-20
+
+DEPENDENCIES
+  actionview (~> 5.0)
+  minitest (~> 5.14)
+  rake (~> 12.0)
+  rubocop-github!
+
+BUNDLED WITH
+   2.2.33