Github Actions: add linter workflow

Author: blocknotes

.github/workflows/linters.yml

@@ -0,0 +1,24 @@
+name: Linters
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  linters:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '2.7'
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+      - name: Install Rubocop
+        run: gem install rubocop rubocop-rspec
+      - name: Check code
+        run: rubocop