Prevent crash when receiving GET requests

[Anulo2]

context: https://discord.com/channels/353303527587708932/752593231681683657/1224110662247121088

was trying to do some http requests to intiface-engine to see if it supported it and the sw crashed. It should only handle ws requests and ignore http methods to prevent these crashes

replicate the bug:

start intiface-engine

In another terminal:

curl http://localhost:12345

error log:

024-03-31T21:59:12.692338Z TRACE tungstenite::handshake::server: Server handshake initiated.
2024-03-31T21:59:12.692350Z TRACE tungstenite::handshake::machine: Doing handshake round.
2024-03-31T21:59:12.692452Z ERROR buttplug::core::connector::transport::websocket::websocket_server: Websocket server accept error: Protocol(MissingConnectionUpgradeHeader)
2024-03-31T21:59:12.692510Z ERROR intiface_engine::engine: Process Error: ConnectorError("TransportSpecificError(TungsteniteError(Protocol(MissingConnectionUpgradeHeader)))")
2024-03-31T21:59:12.692521Z INFO intiface_engine::engine: Client forcefully disconnected from server.
2024-03-31T21:59:12.692527Z INFO intiface_engine::engine: Breaking out of event loop in order to exit
2024-03-31T21:59:12.692533Z INFO intiface_engine::engine: Shutting down server...
2024-03-31T21:59:12.692570Z INFO intiface_engine::engine: Exiting
2024-03-31T21:59:12.692585Z TRACE buttplug::server::device::server_device_manager_event_loop: Got device command message StopScanning
2024-03-31T21:59:12.692630Z DEBUG buttplug::server::device::server_device_manager_event_loop: Device event loop cancelled, exiting.
2024-03-31T21:59:12.692638Z DEBUG buttplug::server::device::server_device_manager_event_loop: Exiting Device Manager Loop
2024-03-31T21:59:12.694270Z ERROR buttplug::server::device::hardware::communication::btleplug::btleplug_adapter_task: Stop scanning request failed: No discovery started
2024-03-31T21:59:12.694286Z DEBUG buttplug::server::device::hardware::communication::btleplug::btleplug_adapter_task: Command stream closed. Exiting btleplug adapter loop.
2024-03-31T21:59:12.794684Z INFO buttplug::server::device::server_device_manager: Dropping device manager!

[qdot]

Yeah the engine gets VERY unhappy when the handshake is wrong. I'm gonna close this because this issue is actually back in the main library: buttplugio/buttplug#570