ci: bump image template to refresh CA certificates

At the end of September 2021, Let's Encrypt's DST Root CA X3
certificate expired, and the new ISRG Root X1 took over.
Update the CI template so that the new certificate is available and we
can keep on cloning the libmbim/libqmi/libqrtr-glib repos without
failures.

(cherry picked from commit 7c30471d)