Workaround StrEnum incompatibility in 3.10 and 3.11

src/pvi/_format/widget.py

@@ -1,8 +1,8 @@
 from __future__ import annotations
 
+import sys
 from collections.abc import Callable
 from dataclasses import dataclass, field
-from enum import StrEnum
 from typing import Any, Generic, TypeVar
 
 from typing_extensions import Self
@@ -26,6 +26,12 @@
     WidgetUnion,
 )
 
+if sys.version_info >= (3, 11):
+    from enum import StrEnum
+else:
+    from enum import Enum
+
+
 T = TypeVar("T")
 
 
@@ -170,7 +176,13 @@ class SubScreenWidgetFormatter(WidgetFormatter[T]):
     macros: dict[str, str] = field(default_factory=dict)
 
 
-class GroupType(StrEnum):
+if sys.version_info >= (3, 11):
+    GroupTypeCls = StrEnum
+else:
+    GroupTypeCls = (str, Enum)
+
+
+class GroupType(GroupTypeCls):
     GROUP = "GROUP"
     SCREEN = "SCREEN"