ai: Lock Gradio version to 5.34.2 for now.

* Latest version (5.35.0, released on Jun 28, 2025),
has a pretty annoying bug.

* Which breaks the stop function. Revert to the old
version for now, until it's fixed.

requirements.txt

@@ -1,6 +1,6 @@
 aiohttp[speedups]
 anyio
-gradio
+gradio==5.34.2
 httpx
 httpx[http2]
 pydantic