Update Azure Pipelines to use Fedora 31
nodejs:12 requires libicu-65.1 while gdb (not direct dependency)
libicu-63.2. As a workaround gdb-minimal  could be used.
It's even better as requires less packages to be downloaded
and then installed.
Co-authored-by: Stanislav Levin <firstname.lastname@example.org>
Signed-off-by: Stanislav Levin <email@example.com>
Reviewed-By: Christian Heimes <firstname.lastname@example.org>