fix: prevent division by 0 for missing total pages
As it turns out the Gitlab api is not guaranteed to return the x-total-pages header for larger query result which previously resulted in a division by zero for pkgctl search as the utlity function assumed that this value would always be set to a positive integer.
Fixes #255
Link: https://gitlab.com/gitlab-org/gitlab/-/issues/436373
Component: gitlab.sh
Signed-off-by: Christian Heusel christian@heusel.eu