Add Rails 7.0 GitHub Action workflow

Author: Mattia Roccoberton

.github/workflows/specs3.yml

@@ -0,0 +1,40 @@
+---
+name: Specs Rails 7.0
+
+on:
+  pull_request:
+    branches: [master]
+  push:
+    branches: [master]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        ruby: ['2.7', '3.0']
+        gemfile: ['rails70_activeadmin']
+
+    env:
+      BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/${{ matrix.gemfile }}.gemfile
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+
+      - name: Run tests
+        run: bundle exec rspec --profile
+
+      - name: On failure, archive screenshots as artifacts
+        uses: actions/upload-artifact@v2
+        if: failure()
+        with:
+          name: test-failed-screenshots
+          path: spec/dummy/tmp/screenshots