add build action

.forgejo/workflows/actions.yml

@@ -0,0 +1,11 @@
+on: [push]
+jobs:
+  test:
+    runs-on: docker
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup dotnet
+        uses: https://github.com/actions/setup-dotnet@v4
+        with:
+          dotnet-version: '4.5'
+      - run: dotnet build