Add GitHub Actions workflow

.github/workflows/build.yml

@@ -0,0 +1,35 @@
+name: Build AUModdedRegions
+
+on:
+  push:
+    branches:
+      - nightly
+  pull_request:
+    branches:
+      - nightly
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout du code
+      uses: actions/checkout@v4
+
+    - name: Configuration de .NET 6
+      uses: actions/setup-dotnet@v4
+      with:
+        dotnet-version: '6.0.x'
+
+    - name: Restauration des dépendances
+      run: dotnet restore
+
+    - name: Build du plugin (Release)
+      run: dotnet build --configuration Release --no-restore
+
+    - name: Sauvegarde du fichier .dll (Artifact)
+      uses: actions/upload-artifact@v4
+      with:
+        name: AUModdedRegions-Nightly
+        path: bin/Release/net6.0/AUModdedRegio
+        ns.dll