use Enum instead of StrEnum for python3.10

src/ldaptool/_main.py

@@ -14,7 +14,7 @@ from ldaptool._utils import argclasses
 from ldaptool._utils.ldap import Result, SizeLimitExceeded
 
 
-class TableOutput(enum.StrEnum):
+class TableOutput(enum.Enum):
     MARKDOWN = "markdown"
     CSV = "csv"
     HTML = "html"