fix: replace Python 3.10+ type hint dict | None with `t.Optional[di…

…ct]` for Python 3.9 compatibility

src/hrflow_connectors/v2/connectors/bullhorn/connector.py

@@ -15,7 +15,7 @@ def to_int(elm: t.Any) -> int:
     return int(elm)
 
 
-def get_location(info: dict) -> dict | None:
+def get_location(info: dict) -> t.Optional[dict]:
     if info:
         location = info.get("location")
         if location is None: