fix: change shebang from /usr/bin/python to /usr/bin/env python in generate scripts

Update the shebang line in both generate_corelib.py and generate_docs.py scripts to use
/usr/bin/env python instead of hardcoded /usr/bin/python, improving portability across
different Python installations and virtual environments.

script/generate_docs.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 import glob
 import markdown