build: requires setuptools-scm

[DimitriPapadopoulos]

No description provided.

[coveralls]

coverage: 99.822%. remained the same
when pulling ced6bec on DimitriPapadopoulos:requires_setuptools-scm
into fd8ddee on adrienverge:master.

[adrienverge]

About the first commit build: format requires as in setuptools doc, the mentioned documentation shows various examples, including a majority of "one space on each side":

BazSpam == 1.1
pywin32 >= 1.0

Moreover the "one space on each side" style is consistent with the dependencies section. So I propose to drop this change.

About the second commit build: requires setuptools-scm, I'm pretty sure you are right to add it, but I (and potential reviewers of this PR) don't have the reason. Can you document why inside the commit message?
(I see a note about setuptools-scm on https://setuptools.pypa.io/en/latest/userguide/dependency_management.html, but it's not explicit why it would apply to yamllint.)

[DimitriPapadopoulos]

I'll drop the first commit.

As for the second commit, I thought setuptools_scm is used by yamllint, but it is not. Maybe an effect of my mixing versions of pip/python?