Simplify CI pipeline for fork

.github/workflows/build.yml

@@ -0,0 +1,27 @@
+name: Build ErsatzTV
+
+on:
+  push:
+    branches: [ main ]
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '8.0.x'
+
+      - name: Restore
+        run: dotnet restore
+
+      - name: Build
+        run: dotnet build --configuration Release --no-restore