Small, easy, low-hanging suggestions when wondering how to speed up our
release process.
- CI: Use multithreading in tarball xz compression
It looks like this compression takes about ~2 minutes. If we use 4 cores
then maybe this will be ~30 seconds + nonlinearity overhead.
- CI: Use trial --jobs=6 instead of -j2 for debs
Other than matching regular CI, this might take off 3~4 min.
Other than that, some caching for the release artifacts step and using
bigger runners to speed up the tests more might help, but those are more
invasive changes.
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Signed-off-by: Olivier 'reivilibre <oliverw@matrix.org>