Handle qsm bindings missing from most pyqt6 versions

Author: krokosik

qtpy/QtStateMachine.py

@@ -45,6 +45,13 @@
         QMouseEventTransition,
     )
 elif PYQT6:
-    from PyQt6.QtStateMachine import *
+    from PyQt6.QtCore import PYQT_VERSION_STR
+
+    if int(PYQT_VERSION_STR.split(".")[1]) >= 9:
+        from PyQt6.QtStateMachine import *
+    else:
+        from . import QtBindingInNewerVersionError
+
+        raise QtBindingInNewerVersionError(name="QtStateMachine")
 elif PYSIDE6:
     from PySide6.QtStateMachine import *

qtpy/__init__.py

@@ -125,6 +125,12 @@ class QtBindingMissingModuleError(QtModuleNotFoundError):
     _msg_extra = "It is not currently implemented in {binding}."
 
 
+class QtBindingInNewerVersionError(QtModuleNotFoundError):
+    """Raised when a module is only supported in newer versions of a binding."""
+
+    _msg_extra = "It is only available in newer versions of {binding}."
+
+
 class QtModuleNotInstalledError(QtModuleNotFoundError):
     """Raise when a module is supported by the binding, but not installed."""