add: dotnet test workflow

.gitea/workflows/test.yaml

@@ -0,0 +1,10 @@
+name: Dotnet test
+on: [push]
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository code
+        uses: https://git.rrricardo.top/actions/checkout@v3
+
+      - run: dotnet test