CLI: update subcommands to use return instead of exit() (#10323)

lib/python/qmk/cli/doctor.py

@@ -364,3 +364,5 @@ def doctor(cli):
     else:
         cli.log.info('{fg_yellow}Problems detected, please fix these problems before proceeding.')
         # FIXME(skullydazed/unclaimed): Link to a document about troubleshooting, or discord or something
+
+    return ok