Migrate from vcversioner to setuptools-scm

It's started at "(while i'm in the repository ¯_(ツ)_/¯)"...

In the process, some more stuff needed to be done:

• drop the symbolic links on the tests data resource folder which would not agree with setuptools-scm otherwise [1]

• add mypy stanza to ignore tenacity stuff (so i could commit)

• [1] https://forge.softwareheritage.org/D3458#84993

Related to swh-environment#2105 (closed)

Test Plan

tox

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Migrated from D3458 (view on Phabricator)