fix: incorrect type hints in a few places (#33104)

xmodule/partitions/partitions_service.py

@@ -3,13 +3,12 @@ This is a service-like API that assigns tracks which groups users are in for var
 user partitions.  It uses the user_service key/value store provided by the LMS runtime to
 persist the assignments.
 """
-
-
 import logging
 from typing import Dict
 
 from django.conf import settings
 from django.contrib.auth import get_user_model
+from opaque_keys.edx.keys import CourseKey
 from openedx.core.lib.cache_utils import request_cached
 from openedx.core.lib.dynamic_partitions_generators import DynamicPartitionGeneratorsPluginManager
 
@@ -44,7 +43,7 @@ def get_all_partitions_for_course(course, active_only=False):
     return all_partitions
 
 
-def get_user_partition_groups(course_key: str, user_partitions: list, user: User,
+def get_user_partition_groups(course_key: CourseKey, user_partitions: list, user: User,
                               partition_dict_key: str = 'name') -> Dict[str, Group]:
     """
     Collect group ID for each partition in this course for this user.