python3-git: upgrade 3.1.36 -> 3.1.37

python3-git: upgrade 3.1.36 -> 3.1.37

License-Update: remove excess whitespace

Changelog:
==========
-Improve Python version and OS compatibility, fixing deprecations
-Better document env_case test/fixture and cwd
-Remove spurious executable permissions
-Fix up checks in Makefile and make them portable
-Fix URLs that were redirecting to another license
-Assorted small fixes/improvements to root dir docs
-Use venv instead of virtualenv in test_installation
-Omit py_modules in setup
-Don't track code coverage temporary files
-Configure tox
-Format tests with black and auto-exclude untracked paths
-Upgrade and broaden flake8, fixing style problems and bugs
-Fix rollback bug in SymbolicReference.set_reference
-Remove @NoEffect annotations
-Add more checks for the validity of refnames

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>