chore: update proctoring to 4.8.1

this completes the drop of the old attempt history table

MST-963

common/djangoapps/util/tests/test_db.py

@@ -1,6 +1,5 @@
 """Tests for util.db module."""
 
-import unittest
 from io import StringIO
 
 import ddt
@@ -122,9 +121,6 @@ class MigrationTests(TestCase):
     """
 
     @override_settings(MIGRATION_MODULES={})
-    @unittest.skip(
-        "Temporary skip for MST-963 while the old proctored exam attempt history is removed"
-    )
     def test_migrations_are_in_sync(self):
         """
         Tests that the migration files are in sync with the models.