keep uvicorn idle connections open longer than nginx's upstream keepalive

uvicorn closed idle connections after its 5s default while nginx kept them pooled for 60s, so a request nginx sent on a connection uvicorn was closing got a 502. nginx retries that on a fresh connection for most methods, but not for POST or PATCH.

frigate/app.py

@@ -731,6 +731,8 @@ class FrigateApp:
                 host="127.0.0.1",
                 port=5001,
                 log_level="error",
+                # outlive nginx's 60s upstream keepalive so nginx closes idle connections first
+                timeout_keep_alive=75,
             )
         finally:
             self.stop()