Add pep8 config file for python

There were some attempts to format python code with pep8 in the past
(tdf#99145).
This adds a config file and sets the max line length to 100
(what we use in clang-format).

Change-Id: I07837af0f6fd6fb108fcfd25c1ba6c6c09a12404
Reviewed-on: https://gerrit.libreoffice.org/60660
Tested-by: Jenkins
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>

setup.cfg

+[pep8]
+max-line-length = 100