Fix strenum import for newer pythons

src/palace/manager/opds/opds2.py

@@ -1,11 +1,11 @@
 from __future__ import annotations
 
+import sys
 from collections.abc import Sequence
 from enum import auto
 from functools import cached_property
 from typing import Annotated, Any, Generic, TypeVar
 
-from backports.strenum.strenum import StrEnum
 from pydantic import (
     AwareDatetime,
     Field,
@@ -27,6 +27,12 @@
 from palace.manager.opds.util import StrOrTuple, obj_or_tuple_to_tuple
 from palace.manager.util.datetime_helpers import utc_now
 
+# TODO: Remove this when we drop support for Python 3.10
+if sys.version_info >= (3, 11):
+    from enum import StrEnum
+else:
+    from backports.strenum import StrEnum
+
 
 def validate_self_link(value: CompactCollection[LinkT]) -> CompactCollection[LinkT]:
     """

src/palace/manager/opds/palace.py

@@ -1,9 +1,16 @@
-from backports.strenum import StrEnum
+import sys
+
 from pydantic import Field, field_validator
 
 from palace.manager.opds.base import BaseOpdsModel
 from palace.manager.util.log import LoggerMixin
 
+# TODO: Remove this when we drop support for Python 3.10
+if sys.version_info >= (3, 11):
+    from enum import StrEnum
+else:
+    from backports.strenum import StrEnum
+
 
 class PublicationTypes(StrEnum):
     """

src/palace/manager/opds/rwpm.py

@@ -1,12 +1,12 @@
 from __future__ import annotations
 
+import sys
 from collections.abc import Sequence
 from datetime import date
 from enum import auto
 from functools import cached_property
 from typing import Literal, TypeVar
 
-from backports.strenum import StrEnum
 from pydantic import AwareDatetime, Field, NonNegativeInt, PositiveFloat, PositiveInt
 
 from palace.manager.opds.base import BaseOpdsModel
@@ -19,6 +19,12 @@
     obj_or_tuple_to_tuple,
 )
 
+# TODO: Remove this when we drop support for Python 3.10
+if sys.version_info >= (3, 11):
+    from enum import StrEnum
+else:
+    from backports.strenum import StrEnum
+
 
 class Encryption(BaseOpdsModel):
     """