Add .NET Core CI workflow

A new workflow for Continuous Integration (CI) of .NET Core has been added to the project. It gets triggered on each push to the master branch, sets up .NET, restores dependencies, builds the project, and runs tests.

.github/workflows/dotnet.yml

@@ -0,0 +1,27 @@
+name: .NET Core CI
+
+on:
+  push:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v2
+        with:
+          dotnet-version: 8.0.x
+
+      - name: Restore dependencies
+        run: dotnet restore
+
+      - name: Build
+        run: dotnet build --no-restore
+
+      - name: Test
+        run: dotnet test --no-build