Modernize GitHub Actions setup, pin actions by SHA, and add a RuboCop baseline

.github/workflows/ci.yml

@@ -7,10 +7,16 @@ on:
     branches: [ master ]
   schedule:
     - cron: '0 0 * * 1' # At 00:00 on Monday.
+  workflow_dispatch:
 
 permissions:
   contents: read
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 jobs:
   Shared:
-    uses: fog/.github/.github/workflows/ci.yml@v1.5.0
+    # fog/.github v1.6.0
+    uses: fog/.github/.github/workflows/ci.yml@f71b6243d92cf84c2307959de3016e0fb7b3411c

.github/workflows/linting.yml

@@ -1,20 +1,27 @@
-# This workflow uses actions that are not certified by GitHub.
-# They are provided by a third-party and are governed by
-# separate terms of service, privacy policy, and support
-# documentation.
-
 name: Linting
 
-on: [push]
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 jobs:
   rubocop:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v7
-      - uses: ruby/setup-ruby@v1
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: ruby/setup-ruby@95ef2b042f9d7a56d8268cba8559e2842e2ad01b # v1.321.0
         with:
-          ruby-version: 3.0
-      - run: bundle install
-      - name: rubocop runs
-        run: rubocop
+          ruby-version: '3.4'
+          bundler-cache: true
+      - name: Run RuboCop
+        run: bundle exec rubocop

.rubocop.yml

@@ -1,3 +1,5 @@
+inherit_from: .rubocop_todo.yml
+
 # Opt-in new cops
 AllCops:
   NewCops: enable