fix(git-prompt): make `gitstatus.py` python3-compatible (#9186)
fix(git-prompt): make `gitstatus.py` python3-compatible (#9186)

check_output() in get_tagname_or_hash() returns bytes instead of str in
python3.  Decode the return value to utf-8, this works in both python2
and python3.

Co-authored-by: Stimim Chen <5413a119f383c3f4549c3ef659403f393bf06e9d@google.com>
tekniklr/oh-my-zsh,tekniklr/oh-my-zsh