Mismatch requirements between gitpython and gitdb

[fmigneault]

Since:
gitpython-developers/gitdb@db9a65e#diff-cb33ff3d8cc897a097528366a431b077

gitdb.utils.compat doesn't exist
This makes any version prior to https://github.com/gitpython-developers/GitPython/tree/3.0.6
to fail because the requirement is not limited to <3.0.2 in the requirements :
https://github.com/gitpython-developers/GitPython/blob/3.0.6/requirements.txt

[Harmon758]

Duplicate of #983