'updateinfo list' tests for dnf5 have to respect used time zone

[glum23]

The output of dnf5 updateinfo list depends on the currently set time zone, namely 'Issued' time of advisories is transformed from (supposed) universal time to the local time.

# timedatectl set-timezone America/Phoenix
# dnf5 updateinfo list
Name                   Type        Severity                                    Package              Issued
FEDORA-2023-3630891bed enhancement Moderate                 make-1:4.4.1-1.fc38.x86_64 2023-09-13 18:27:18
FEDORA-2023-6a22f9d0ca enhancement Low         cloud-utils-growpart-0.33-3.fc38.noarch 2023-09-16 18:25:42
# timedatectl set-timezone Europe/Prague
# dnf5 updateinfo list
Name                   Type        Severity                                    Package              Issued
FEDORA-2023-3630891bed enhancement Moderate                 make-1:4.4.1-1.fc38.x86_64 2023-09-14 03:27:18
FEDORA-2023-6a22f9d0ca enhancement Low         cloud-utils-growpart-0.33-3.fc38.noarch 2023-09-17 03:25:42

According to rpm-software-management/dnf5#900 dnf5 behavior is intentional. Upstream tests updateinfo.feature and security-upgrade.feature (both tagged as dnf5) have to be changed. They fail when the local time is different from the universal time.