github actions workflow

.github/workflows/build.yml

@@ -0,0 +1,27 @@
+name: build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macOS-latest]
+        dotnet: [3.1.201]
+    runs-on: ${{ matrix.os }}
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Setup .NET Core
+      uses: actions/setup-dotnet@v1
+      with:
+        dotnet-version: ${{ matrix.dotnet }}
+    - name: Restore tools
+      run: dotnet tool restore
+    - name: Restore dependencies
+      run: dotnet restore
+    - name: Build
+      run: dotnet fake build
+#    - name: Test
+#      run: dotnet test --no-restore --verbosity normal