CI: build/test separately

.github/workflows/dotnetcore.yml

@@ -13,5 +13,17 @@ jobs:
       uses: actions/setup-dotnet@v1
       with:
         dotnet-version: 5.0.x
-    - name: Build and test with dotnet
+    - name: Build with dotnet
+      run: dotnet build --configuration Release
+  test:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+      with:
+        submodules: recursive
+    - name: Setup .NET Core
+      uses: actions/setup-dotnet@v1
+      with:
+        dotnet-version: 5.0.x
+    - name: Run automated tests
       run: dotnet test --configuration Release