Consider using both bump2version and setuptool_scm

[adamltyson]

An excellent idea from @dstansby:

maybe a good way to go would be to use both, and use bump2version to just set the git tag correctly, with setuptools_scm handling setting the Python package version from the git tag?

We should test this. In theory this should allow for the nice bits of bump2version such as being able to set the version semantically rather than numerically, but without the complex setup to define what gets updated and where.

This should also hopefully future proof us a bit to changes in python packaging.

cc @SainsburyWellcomeCentre/neuroinformatics-unit

[niksirbi]

That sounds like a great idea if it actually works in practice, without the two tools clashing

[JoeZiminski]

Interesting discussion on this here, in the end I believe they have also taken this joint approach.

[adamltyson]

Now gone with only setuptools_scm. Need to document this (and remove the bump2version docs).

[adamltyson]

setuptools_scm is now documented