Python 3.6 is already the default Python in the jobs that are based
on Ubuntu Bionic, so it does not make much sense to test this again
separately.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200918103430.297167-7-thuth@redhat.com>
Message-Id: <20200925154027.12672-8-alex.bennee@linaro.org>