chore: bump manifest version and remove tests workflow

Update the integration manifest version to v2026.3.1 and remove the tests.yaml GitHub Actions workflow as requested.

Author: Desmond-Dong

.github/workflows/tests.yaml

@@ -9,5 +9,5 @@
   "iot_class": "cloud_polling",
   "issue_tracker": "https://github.com/ha-china/ai_hub/issues",
   "requirements": ["edge-tts==7.2.7", "aiofiles", "aiohttp"],
-  "version": "v2026.3.0"
+  "version": "v2026.3.1"
 }