Always expect pagination for GETs

[gdubicki]

as it happened a few times already that we didn't mark an API as using
pagination initially and it caused problems for some users. According
to GitLab's API docs (https://docs.gitlab.com/ee/api/#pagination)
the pagination "is available on all endpoints", so let's just pass
the for all GETs.

Fixes #354.

[codecov]

Codecov Report

Merging #358 (1536d62) into main (20e2644) will not change coverage.
The diff coverage is 80.00%.

@@           Coverage Diff           @@
##             main     #358   +/-   ##
=======================================
  Coverage   80.92%   80.92%           
=======================================
  Files          63       63           
  Lines        2433     2433           
=======================================
  Hits         1969     1969           
  Misses        464      464           

Impacted Files	Coverage Δ
gitlabform/gitlab/branches.py	86.76% <ø> (ø)
gitlabform/gitlab/merge_requests.py	53.33% <ø> (ø)
gitlabform/gitlab/pipelines.py	45.45% <ø> (ø)
gitlabform/gitlab/projects.py	55.14% <0.00%> (ø)
gitlabform/gitlab/tags.py	100.00% <ø> (ø)
gitlabform/gitlab/core.py	92.36% <100.00%> (ø)
gitlabform/gitlab/groups.py	87.93% <100.00%> (ø)
gitlabform/gitlab/members.py	97.61% <100.00%> (ø)