Fix format_check.py failing on Windows with Python 3.7 (#6188)
Fix format_check.py failing on Windows with Python 3.7 (#6188)

- The output from the git subprocess has to be decoded from bytes
  to str before passing it as an argument of a new subprocess.

- Use the python interpreter of the current script to run git-clang-format.py.
hackgnar/osquery,hackgnar/osquery,hackgnar/osquery