Support TestRail bulK api end point pagination introduced in version 6.7 and later

https://blog.gurock.com/announcing-testrail-6-7/

The full list of bulk API endpoints that include this change are below:

get_cases
get_runs
get_results
get_tests
get_results_for_case
get_results_for_run
get_plans
get_projects
get_sections
get_milestones
get_history_for_case
get_attachments_for_case
get_attachments_for_run
get_attachments_for_plan