fix: disable uvicorn ws_ping_interval/timeout to prevent WebSocket disconnects

Uvicorn's default ws_ping_interval=20 / ws_ping_timeout=20 can
non-deterministically close local WebSocket connections (e.g. NWC provider
↔ nostrclient relay) under event-loop load. The client side already sends
its own pings, so server-side pings are redundant here.

See discussion:
https://github.com/lnbits/nostrclient/pull/71#issuecomment-4803033307

lnbits/server.py

@@ -58,6 +58,8 @@ def main(
             ssl_keyfile=ssl_keyfile,
             ssl_certfile=ssl_certfile,
             reload=reload or False,
+            ws_ping_interval=None,
+            ws_ping_timeout=None,
         )
 
         server = uvicorn.Server(config=config)