test: add tag trigger test workflow

.gitea/workflows/test-tag.yaml

@@ -0,0 +1,15 @@
+name: Tag Trigger Test
+on:
+  push:
+    tags:
+      - "test-*"
+jobs:
+  test:
+    runs-on: shell
+    steps:
+      - name: Test
+        run: |
+          echo "Tag trigger works!"
+          echo "Ref: ${{ gitea.ref_name }}"
+          echo "Time: $(date)"
+          date | sudo tee -a /tmp/tag-test.log