Add rubocop checks

Author: route

.github/workflows/linter.yml

@@ -0,0 +1,37 @@
+name: Linter
+on: [push]
+
+jobs:
+   linters:
+     name: Linters
+     strategy:
+       fail-fast: false
+       matrix:
+         ruby: [ 2.7, 3.0 ]
+     runs-on: ubuntu-latest
+     steps:
+       - name: Checkout code
+         uses: actions/checkout@v2
+
+       - name: Setup Ruby
+         uses: ruby/setup-ruby@v1
+         with:
+           ruby-version: ${{ matrix.ruby }}
+           bundler-cache: true
+
+       - name: Ruby gem cache
+         uses: actions/cache@v1
+         with:
+           path: vendor/bundle
+           key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile.lock') }}
+           restore-keys: |
+             ${{ runner.os }}-gems-
+
+       - name: Install gems
+         run: |
+           bundle config path vendor/bundle
+           bundle install --jobs 4 --retry 3
+
+       - name: Run linters
+         run: |
+           bundle exec rubocop --parallel

.github/workflows/tests.yml

@@ -8,13 +8,11 @@ on:
 jobs:
   tests:
     name: Tests
-
     strategy:
       fail-fast: false
       matrix:
         gemfile: [websocket-driver-0.6.x, websocket-driver-0.7.x]
         ruby: [2.6, 2.7, 3.0]
-
     runs-on: ubuntu-latest
     env:
       FERRUM_PROCESS_TIMEOUT: 20