[clang-format] Update the minimum python version requirement

See https://llvm.org/docs/GettingStarted.html#software

Fix #131456

Author: owenca

clang/tools/clang-format/git-clang-format

@@ -19,7 +19,7 @@ clang-format on the changes in current files or a specific commit.
 For further details, run:
 git clang-format -h
 
-Requires Python 2.7 or Python 3
+Requires Python version >=3.8
 """
 
 from __future__ import absolute_import, division, print_function