Start 6.0.0 version (#768)

* Drop ruby 2.x support

* Start new Changelog

* New filename: CHANGELOG.md
* Following KeepAChangelog.com convention
* Pre 6.0.0 changelog renamed from CHANGES to CHANGES_OLD

* Update rubocop

* Lock rubocop-* gems

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
 
     strategy:
       matrix:
-        ruby: [ ruby-2.6, ruby-2.7, ruby-3.0, ruby-3.1, ruby-3.2 ]
+        ruby: [ ruby-3.0, ruby-3.1, ruby-3.2 ]
         os: [ ubuntu-latest ]
 
     steps:
@@ -43,7 +43,7 @@ jobs:
 
     strategy:
       matrix:
-        ruby: [ jruby-9.3 ]
+        ruby: [ jruby-9.4 ]
         os: [ ubuntu-latest ]
 
     steps:
@@ -76,7 +76,7 @@ jobs:
 
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 2.6
+          ruby-version: ruby-3.0
           bundler-cache: true
 
       - name: bundle exec rubocop

.rubocop.yml

@@ -1,3 +1,8 @@
+require:
+  - rubocop-performance
+  - rubocop-rake
+  - rubocop-rspec
+
 inherit_from:
   - .rubocop_todo.yml
   - .rubocop/layout.yml
@@ -7,5 +12,6 @@ inherit_from:
 AllCops:
   DefaultFormatter: fuubar
   DisplayCopNames: true
+  DisplayStyleGuide: true
   NewCops: enable
-  TargetRubyVersion: 2.6
+  TargetRubyVersion: 3.0

.rubocop/metrics.yml

@@ -1,4 +1,26 @@
 Metrics/BlockLength:
+  CountAsOne:
+    - array
+    - heredoc
+    - method_call
   Exclude:
     - 'spec/**/*.rb'
-    - '*.gemspec'
+    - '*.gemspec'
+
+Metrics/ClassLength:
+  CountAsOne:
+    - array
+    - heredoc
+    - method_call
+
+Metrics/MethodLength:
+  CountAsOne:
+    - array
+    - heredoc
+    - method_call
+
+Metrics/ModuleLength:
+  CountAsOne:
+    - array
+    - heredoc
+    - method_call

.rubocop/style.yml

@@ -17,6 +17,10 @@ Style/HashSyntax:
 Style/OptionHash:
   Enabled: true
 
+# Using explicit `./` makes code more consistent
+Style/RedundantCurrentDirectoryInPath:
+  Enabled: false
+
 Style/RescueStandardError:
   Enabled: true
   EnforcedStyle: implicit