asyncutils: Remove os.environ modification for qasync initialization

Since qasync>=0.10.0 it correctly handles case insensitive QT_API env
variables.

orangecanvas/utils/asyncutils.py

@@ -1,9 +1,9 @@
-import os
 import asyncio
 from concurrent import futures
 from typing import Optional
 
 from AnyQt.QtCore import QCoreApplication, QThread
+import qasync
 
 
 def get_event_loop() -> asyncio.AbstractEventLoop:
@@ -32,13 +32,6 @@ def get_event_loop() -> asyncio.AbstractEventLoop:
         if loop is not None:
             return loop
 
-    qt_api = os.environ.get("QT_API", "").lower()
-    if qt_api == "pyqt5":
-        os.environ["QT_API"] = "PyQt5"
-    elif qt_api == "pyside2":
-        os.environ["QT_API"] = "PySide2"
-    import qasync
-
     if loop is None:
         loop = qasync.QEventLoop(app)
         # Do not use qasync.QEventLoop's default executor which uses QThread

setup.py

@@ -30,7 +30,7 @@
     "cachecontrol[filecache]",
     "pip>=18.0",
     "dictdiffer",
-    "qasync",
+    "qasync>=0.10.0",
     "importlib_metadata; python_version<'3.8'",
 )