Fix Rubocop workflow

.github/workflows/ci.yml

@@ -14,7 +14,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-        - { ruby: 2.6 }
         - { ruby: 2.7 }
 
     steps:

.github/workflows/rubocop.yml

@@ -4,17 +4,23 @@ on: [pull_request]
 
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
+    env:
+      BUNDLE_ONLY: rubocop
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
 
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 2.6
+        ruby-version: 2.7
+
+    - run: |
+        gem install securerandom -v 0.3.2
+        gem install activesupport -v 7.1.5.1
 
     - name: Run RuboCop linter
-      uses: reviewdog/action-rubocop@v1
+      uses: reviewdog/action-rubocop@v2
       with:
         github_token: ${{ secrets.github_token }}
         reporter: github-pr-review

.rubocop.yml

@@ -11,7 +11,7 @@ AllCops:
     - 'bin/rubocop'
   NewCops: enable
   SuggestExtensions: false
-  TargetRubyVersion: 2.6
+  TargetRubyVersion: 2.7
 
 Metrics/BlockLength:
   Exclude:

Gemfile.lock

@@ -117,7 +117,9 @@ GEM
     zeitwerk (2.4.2)
 
 PLATFORMS
+  arm64-darwin
   ruby
+  x82_64-darwin
 
 DEPENDENCIES
   icasework!

icasework.gemspec

@@ -13,7 +13,7 @@ Gem::Specification.new do |spec|
     'organisations of all sizes to do a better job of case management'
   spec.homepage      = 'https://github.com/mysociety/icasework-ruby/'
   spec.license       = 'MIT'
-  spec.required_ruby_version = Gem::Requirement.new('>= 2.6.0')
+  spec.required_ruby_version = Gem::Requirement.new('>= 2.7.0')
 
   spec.metadata['allowed_push_host'] = 'https://rubygems.org'