* Move `pympler` back into the `all` extras

Undoes a change I made in #12381. I can't fully remember my reasoning,
but this changed the contents of the debian packages in a backwards
incompatible way. We're not aware of anyone who's been bitten by this,
but we still want to fix it.

To the reviewer: please be convinced that the debian packages will still
contain pympler after this change.

* Debian changelog entry to keep the linter happy

Not enforced in config yet. One day.

* Specify `tls` extra for Twisted dependency.

It was already pulled in for us by `treq`, but we should be explicit
that we do use the `tls` functionality of Twisted directly.

* Mark `idna` as dev-dependency

This doesn't actually change anything, as `Twisted[tls]` will put it in
as a main dependency anyway.

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

* update black version

* run updated version of black on code

* newsfragment

* enumerate python versions

Signed-off-by: Dan Callahan <danc@element.io>

This allows trailing commas in multi-line arg lists.

Minor, but we might as well keep our formatting current with regard to
our minimum supported Python version.

Signed-off-by: Dan Callahan <danc@element.io>

... and certain other changelog-related fixes

* Add a few more common environment directory names to black exclusion

* Add changelog