Use GitHub Actions for CI

Author: mrkn

.github/workflows/ci.yml

@@ -0,0 +1,43 @@
+name: CI
+
+on:
+- push
+
+jobs:
+  cruby:
+    name: Test
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+        - ubuntu-latest
+        - macos-latest
+        - windows-latest
+        ruby_version:
+        - 3.0.0-preview2
+        - 2.7
+        - 2.6
+        - 2.5
+        - 2.4
+        - debug
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Setup Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby_version }}
+
+    - run: yes | gem update --system
+    - run: gem install bundler
+    - run: bundle install
+
+    - run: rake --trace compile
+
+    - run: rake build
+    - run: gem install pkg/*gem
+
+    - run: rake test