add csproject

.gitea/workflows/ci.yml

@@ -6,10 +6,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: build using gcc
-        run: gcc -Wall -Werror main.c -o program
-      - name: Archive production artifacts
-        uses: actions/upload-artifact@v3
-        with:
-          name: program
-          path: program
+      - uses: actions/setup-dotnet@v3
+          with:
+            dotnet-version: '6.0.x'
+      - run: dotnet restore
+      - run: dotnet build