fix mus 644 extraneous cross listing

Author: reybahl

ferry/transform/import_courses.py

@@ -92,7 +92,6 @@ def get_applicable_key(row: pd.Series):
     ("201803", (12568, 13263)),  # CPLT 942
     ("201901", (21500, 22135)),  # PLSC 530
     ("202403", (15444, 15753)),  # MUS 644
-    ("202503", (11421, 11423)),  # MUS 644 (again)
     ("202503", (10009, 10008)),  # MUS 815
     ("202601", (23900, 23902)),  # MUS 506
     ("202601", (23903, 23904)),  # MUS 606