drop python.exe extension on windows on shebang

pre_commit/commands/install_uninstall.py

@@ -55,7 +55,7 @@ def is_our_script(filename: str) -> bool:
 
 def shebang() -> str:
     if sys.platform == 'win32':
-        py = SYS_EXE
+        py, _ = os.path.splitext(SYS_EXE)
     else:
         exe_choices = [
             f'python{sys.version_info[0]}.{sys.version_info[1]}',