Update CI workflow to use Docker for build and test jobs

.gitea/workflows/ci.yml

@@ -6,7 +6,7 @@ on:
     branches: [ main ]
 jobs:
   build-test:
-    runs-on: ubuntu-latest
+    runs-on: docker
     steps:
       - name: Checkout code
         uses: actions/checkout@v3
@@ -24,5 +24,4 @@ jobs:
             echo "::warning::Test coverage is below 80% ($cov%)"
           fi
       - name: Build Docker image
-        run: docker build -t diun-webhook-dashboard .
-
+        run: docker build -t diun-webhook-dashboard .