Upgrade rubocop to latest version

Author: kytrinyx

Gemfile

@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gem 'minitest'
 gem 'rake'
 gem 'mocha', require: false
-gem 'rubocop', '~> 1.21', require: false
+gem 'rubocop', '~> 1.50.0', require: false
 gem 'rubocop-minitest', require: false
 gem 'rubocop-rake', require: false
 gem 'simplecov', require: false

Gemfile.lock

@@ -3,38 +3,40 @@ GEM
   specs:
     ast (2.4.2)
     docile (1.4.0)
+    json (2.6.3)
     minitest (5.14.4)
     mocha (1.13.0)
-    parallel (1.21.0)
-    parser (3.0.2.0)
+    parallel (1.23.0)
+    parser (3.2.2.1)
       ast (~> 2.4.1)
-    rainbow (3.0.0)
+    rainbow (3.1.1)
     rake (13.0.6)
-    regexp_parser (2.1.1)
+    regexp_parser (2.8.0)
     rexml (3.2.5)
-    rubocop (1.21.0)
+    rubocop (1.50.2)
+      json (~> 2.3)
       parallel (~> 1.10)
-      parser (>= 3.0.0.0)
+      parser (>= 3.2.0.0)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 1.8, < 3.0)
-      rexml
-      rubocop-ast (>= 1.9.1, < 2.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.28.0, < 2.0)
       ruby-progressbar (~> 1.7)
-      unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.11.0)
-      parser (>= 3.0.1.1)
+      unicode-display_width (>= 2.4.0, < 3.0)
+    rubocop-ast (1.28.0)
+      parser (>= 3.2.1.0)
     rubocop-minitest (0.15.0)
       rubocop (>= 0.90, < 2.0)
     rubocop-rake (0.6.0)
       rubocop (~> 1.0)
-    ruby-progressbar (1.11.0)
+    ruby-progressbar (1.13.0)
     simplecov (0.21.2)
       docile (~> 1.1)
       simplecov-html (~> 0.11)
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.12.3)
     simplecov_json_formatter (0.1.3)
-    unicode-display_width (2.1.0)
+    unicode-display_width (2.4.2)
 
 PLATFORMS
   ruby
@@ -43,10 +45,10 @@ DEPENDENCIES
   minitest
   mocha
   rake
-  rubocop (~> 1.21)
+  rubocop (~> 1.50.0)
   rubocop-minitest
   rubocop-rake
   simplecov
 
 BUNDLED WITH
-   2.1.4
+   2.2.22