pytz will be removed from RHEL/CentOS 10 because of the built-in
zoneinfo[1].
Because the current usage of pytz can be very easily replaced, this
removes the dependency on pytz.
[1] https://issues.redhat.com/browse/RHEL-219
Change-Id: Iafcaf2f1095cd7c738dac391a9af10622806e932