Now cygwin seems to have completed a migration of the default python to
3.9, so that is where the devel package is at.
Back out the changes from commit 3304a38496
and update the pip/wheel packages as appropriate.
multiple versions of python are packaged by cygwin, and the default
python is auto-selected as the latest one via a Debian-like alternatives
system.
This recently broke because dblatex is built against 3.9, causing it to
be installed too and resulting in multiple (inconsistent) versions of
python being installed, and `python3` pointing to the one we don't have
devel packages for and isn't even the default version.
Fix this by pointing back to the intended python.
Set MESON_CI_JOBNAME for all CI jobs which run project tests.
(Note that ${{ github.job }} is the literal job.id used in the yaml, not
any name given to the job with job.id.name, and so is the same for all
matrix entries, and thus not suitable for our purposes there).
* CI: Don't run cross-only test when other workflows are changed
* CI: Move Cygwin test run from Azure Pipelines to GitHub workflow
Also review installed package list, dropping detritus from 42792554, not
removed in f5ed85d7.