[Twisted-Python] mypy integrated with CI for twisted

[Kyle Altendorf]

> On 2020-06-24 00:43, Glyph wrote:
> 
> > On Jun 23, 2020, at 5:34 AM, Adi Roiban <adi at roiban.ro> wrote:
> >
> > Hi Craig,
> >
> > On Tue, 23 Jun 2020 at 00:36, Craig Rodrigues <rodrigc at crodrigues.org> wrote:
> > I have merged some more fixes for mypy to Twisted trunk branch.
> >
> > In trunk, you can run mypy with:
> >
> > tox -e mypy
> >
> > Currently this results in 171 errors, which is way down from >1000 errors
> > a month ago.
> >
> > In addition, if you look at any new PR's there is a Mypy Ubuntu job
> > running on Azure pipeline, which runs mypy.  Right now errors from this job
> > are ignored and does not block the PR.  However, if we can get the mypy
> > errors down to zero, we can make mypy status a blocker for the PR.
> >
> > Thanks for working on this.
> >
> > Looking forward to have a real green mypy build.
> >
> > A general question: Why Twisted used Azure Devops and not GitHub actions?
> 
> Azure Pipelines gave us substantially more parallel capacity than is 
> available via Github Actions, which means we can make build statuses 
> appear much sooner.  Plus they support more platforms.

Just noticed we don't actually link to Azure from the readme.  Presently 
we have 14 builds there so within the tense pickiness :] we don't get 
any benefit (yet).

I'm curious though, what additional platforms does Azure get us?