Bug#754287: (no subject)
Yes, you can keep your releases on the GitHub branch.
However, it would be advisable to remove the /debian directory from your
github repository. Even though you may be maintaining both upstream and
with Debian, this may change in the future, and it causes problems if
upstream and Debian have different /debian directories. (Also, it
becomes more difficult to generate the .orig.tar.gz )
*You mentioned that you were using debhelper 9, so you should change
d/compat to 9. (This will also fix the
"missing-dependency-on-python-support" lintian tag.)
*The full text of CC-0 formatted for d/copyright can be found here 
*python-setuptools is required to build, but build-depends lists
python3-setuptools. It appears that this is because some parts of the
d/rules are using python2.7 by default. I've managed to build it without
python-setuptools by making the following modifications:
-In line 10, replace "python setup.py" with "python3 setup.py"
-Add a line "override_dh_auto_configure:"
*You include several lib/ entries in the copyright file, but you do not
distribute them. It is good that you do not distribute them (because
modules should be packaged separately), but these should be removed
from the d/copyright.
*I couldn't find packages for the tzlocal and Delorean modules. These
will have to be packaged first, then added as dependencies. The Python
Modules Team  should be able to help you with this.
*I think that you've got the license GNU right, but I'm not sure. Read
over this IRC log  and note that the icon was originally from here
 and then make a decision for yourself.
After this, I can't really see any more problems. Once you've made the
above corrections, you could perhaps try finding a sponsor with the
Python Applications Packaging Team. 
Good luck in finding a sponsor!