ci: linux CI on GA

.github/workflows/ci.yml

@@ -0,0 +1,27 @@
+name: Continuous Integration
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    types: [opened, synchronize]
+    branches: [main]
+  schedule:
+    - cron: "0 8 * * 5" # At 08:00 on Friday # https://crontab.guru/#0_8_*_*_5
+  workflow_dispatch:
+
+jobs:
+  linux:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby: ["2.3", "2.4", "2.5", "2.6", "2.7", "3.0", "head"]
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: MSP-Greg/setup-ruby-pkgs@v1
+        with:
+          apt-get: _update_ build-essential cmake
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - run: bundle exec rake test