chore: upgrade websockets dependency to support 15+ and update import statements

Author: ttypic

ably/transport/websockettransport.py

@@ -11,8 +11,7 @@
 from ably.util.eventemitter import EventEmitter
 from ably.util.exceptions import AblyException
 from ably.util.helper import Timer, unix_time_ms
-from websockets.client import WebSocketClientProtocol, connect as ws_connect
-from websockets.exceptions import ConnectionClosedOK, WebSocketException
+from websockets import WebSocketClientProtocol, connect as ws_connect, ConnectionClosedOK, WebSocketException
 
 if TYPE_CHECKING:
     from ably.realtime.connection import ConnectionManager

poetry.lock

@@ -40,7 +40,8 @@ httpx = [
 h2 = "^4.1.0" # required for httx package, HTTP2 communication
 websockets = [
   { version = ">= 10.0, < 12.0", python = "~3.7" },
-  { version = ">= 12.0, < 14.0", python = "^3.8" },
+  { version = ">= 12.0, < 15.0", python = "~3.8" },
+  { version = ">= 15.0, < 16.0", python = "^3.9" },
 ]
 pyee = [
   { version = "^9.0.4", python = "~3.7" },