scripts: use plain import of contributor_data Relative import failed with: Traceback (most recent call last): File "scripts/update-copyrights.py", line 45, in <module> from . import contributor_data ImportError: attempted relative import with no known parent package Fixed by backing out changeset 2786730e56e0. The pytype problem can be solved differently.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.