chore: fix invalid SPDX license expression in __init__.py of rest_framework (encode#9799)

Author: TheFunctionalGuy

rest_framework/__init__.py

@@ -10,7 +10,7 @@
 __title__ = 'Django REST framework'
 __version__ = '3.16.1'
 __author__ = 'Tom Christie'
-__license__ = 'BSD 3-Clause'
+__license__ = 'BSD-3-Clause'
 __copyright__ = 'Copyright 2011-2023 Encode OSS Ltd'
 
 # Version synonym