Fix WebSocket proxy ping timeout killing MSE streams

The websockets library defaults to ping_interval=20, ping_timeout=20.
go2rtc doesn't respond to these pings, so the upstream WebSocket was
being killed after ~50 seconds causing all camera streams to freeze.

Disabled ping_interval and ping_timeout on the upstream connection.

backend/routes/go2rtc_proxy.py

@@ -43,7 +43,12 @@ async def proxy_mse_ws(ws: WebSocket, src: str):
     await ws.accept()
 
     try:
-        async with websockets.connect(target) as upstream:
+        async with websockets.connect(
+            target,
+            ping_interval=None,
+            ping_timeout=None,
+            close_timeout=5,
+        ) as upstream:
 
             async def forward_to_client():
                 async for msg in upstream: