chore: add CI (#7)

.github/workflows/master.yml

@@ -0,0 +1,51 @@
+name: Dart CI analyze and test
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+  workflow_dispatch:
+
+jobs:
+  analyze:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dart-lang/setup-dart@v1
+        with:
+          sdk: dev
+
+      - name: Install dependencies
+        run: dart pub get
+
+      - name: Verify formatting
+        run: dart format --output=none --set-exit-if-changed .
+
+      - name: Analyze source code
+        run: dart analyze --fatal-infos
+
+  test:
+    needs: analyze
+    strategy:
+      fail-fast: false
+      matrix:
+        platform: [ubuntu-latest, macos-latest, windows-latest]
+    runs-on: ${{ matrix.platform }}
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dart-lang/setup-dart@v1
+        with:
+          sdk: dev
+
+      - name: Install dependencies
+        run: dart pub get
+
+      - name: Download libgit2 library
+        run: dart run libgit2dart:setup
+
+      - name: Run tests
+        run: dart test