Add GitHub Action to build the mod on each PR (#453)

* missing import

* Create build.yml

.github/workflows/build.yml

@@ -0,0 +1,32 @@
+name: Build
+
+on:
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+
+    - name: Setup .NET
+      uses: actions/setup-dotnet@v3
+      with:
+        dotnet-version: 8.0.x
+
+    - name: Cache NuGet packages
+      uses: actions/cache@v3
+      with:
+        path: ~/.nuget/packages
+        key: ${{ runner.os }}-nuget-${{ hashFiles('**/*.csproj') }}
+        restore-keys: |
+          ${{ runner.os }}-nuget-
+
+    - name: Restore dependencies
+      run: dotnet restore
+
+    - name: Build
+      run: dotnet build --configuration Release --no-restore