[bug] Releaser tool adds any change and pushes it

[nemesifier]

Describe the bug

The releaser tool adds all the files for being committed instead of only adding the files which have been changed.
This is wrong.

I think the problem stems from:

https://github.com/openwisp/openwisp-utils/blob/master/openwisp_utils/releaser/release.py#L361-L362

This dangerous as files which are meant to be private may be pushed by mistake to the repository.

[Srinath0916]

@nemesifier , i would like to take the issue and start to work on it. The git add . on line 361 should only add the specific files that were changed during release, not everything. Can I take this issue?