Bump rubocop from 0.51.0 to 0.54.0

Bumps [rubocop](https://github.com/bbatsov/rubocop) from 0.51.0 to 0.54.0.
- [Release notes](https://github.com/bbatsov/rubocop/releases)
- [Changelog](https://github.com/bbatsov/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v0.51.0...v0.54.0)

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

Gemfile.lock

@@ -2,7 +2,7 @@ GEM
   remote: http://rubygems.org/
   specs:
     addressable (2.4.0)
-    ast (2.3.0)
+    ast (2.4.0)
     backports (3.11.1)
     byebug (10.0.2)
     coderay (1.1.2)
@@ -62,9 +62,9 @@ GEM
     notiffany (0.1.1)
       nenv (~> 0.1)
       shellany (~> 0.0)
-    parallel (1.12.0)
-    parser (2.4.0.2)
-      ast (~> 2.3)
+    parallel (1.12.1)
+    parser (2.5.0.5)
+      ast (~> 2.4.0)
     powerpack (0.1.1)
     pry (0.11.3)
       coderay (~> 1.1.0)
@@ -81,9 +81,8 @@ GEM
       rack
     rack-test (0.8.2)
       rack (>= 1.0, < 3)
-    rainbow (2.2.2)
-      rake
-    rake (12.3.0)
+    rainbow (3.0.0)
+    rake (12.3.1)
     rb-fsevent (0.9.8)
     rb-inotify (0.9.8)
       ffi (>= 0.5.0)
@@ -103,11 +102,11 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.7.0)
     rspec-support (3.7.0)
-    rubocop (0.51.0)
+    rubocop (0.54.0)
       parallel (~> 1.10)
-      parser (>= 2.3.3.1, < 3.0)
+      parser (>= 2.5)
       powerpack (~> 0.1)
-      rainbow (>= 2.2.2, < 3.0)
+      rainbow (>= 2.2.2, < 4.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (~> 1.0, >= 1.0.1)
     ruby-progressbar (1.9.0)