Also format *.hpp files. (#16997)

lib/python/qmk/cli/format/c.py

@@ -9,7 +9,7 @@ from milc import cli
 from qmk.path import normpath
 from qmk.c_parse import c_source_files
 
-c_file_suffixes = ('c', 'h', 'cpp')
+c_file_suffixes = ('c', 'h', 'cpp', 'hpp')
 core_dirs = ('drivers', 'quantum', 'tests', 'tmk_core', 'platforms')
 ignored = ('tmk_core/protocol/usb_hid', 'platforms/chibios/boards')