pin importlib-metadata to 1.7.0 for python35

[UsamaSadiq]

• Pinned importlib-metadata==1.7.0 as version>1.7.0 is causing conflicts for python35 in running make upgrade.

Note:
According to the discussion on #65 by @feanil, tests on python35 are failing because of the older version of importlib-metadata and we'll have to wait for the tox update for this issue to be resolved.
So pinning this package version unless we have a fix for the tests because it is causing the automated package upgrade jobs to fail.

[UsamaSadiq]

Hi @feanil,
importlib-metadata is causing conflicts and hence build failures in the automated python package upgrade jobs. To make the build successful again, I've decided to pin importlib-metadata==1.7.0 for now.
Since you were already working on a fix for the package version issue in this repo, should I wait for your fix in this repo before working on this again & pause the upgrade-job till then, or should I pin the version for now so the upgrade job will run successfully until we can find the fix for this version conflict, in which case I'll need your help in merging this PR because I don't have access to merge this PR without the tests' status as passing?
Thanks.

CC: @jmbowman @awais786

[feanil]

@jmbowman can we drop 3.5 support in the cookiecutter instead? Even if it produces 3.5 code, I don't think the cookiecutter needs to be able to run in python 3.5

[jmbowman]

Sounds good to me, especially if we can still run tests on the generated repo using 3.5 (although we shouldn't need that much longer either).

[UsamaSadiq]

The issue has been fixed in pypa/virtualenv#1953 and tox-dev/tox#1682 so this PR is not needed anymore. Closing this PR.