Upgrading CRT version
- API CHANGE: awscrt.auth.AwsSigningConfig.signed_body_value is now a string instead of an enum.
- API CHANGE: Added check for iOS platform
- BUGFIX: websocket no longer hangs if CLOSE frame cannot be sent.
- BUGFIX: Fixes a crash when shutting down an mqtt connection with an incomplete request with no callback from aws-c-mqtt