Tests:
- Run with new code. Setup is run for upgrades modules.
/etc/apt/preferences.d/51-freedombox-apps.pref contains the changes for
python3-attr.
- On stable. apt policy python3-attr shows version 19.3.0-3~bpo10+1 is the
preferred version.
- On stable, installing matrix-synapse leads to installation of python3-attr
=19.3.0-3~bpo10+1.
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>