Existing listers use the `is_within_bound` [1] method from the base lister.
This method uses inclusive boundaries in all cases.
As some "range" task listers [2] [3] are using `split_range` function to create
"overlapping" ranges. So, when those range overlap, this can create concurrent
insert issues down the line.
This commit adapts the function `split_range` to make the generated ranges no
longer overlap.
[1]
https://forge.softwareheritage.org/source/swh-lister/browse/master/swh/lister/core/lister_base.py$194-199
[2]
https://forge.softwareheritage.org/source/swh-lister/browse/master/swh/lister/gitlab/tasks.py$37-41
[3]
https://forge.softwareheritage.org/source/swh-lister/browse/master/swh/lister/gitea/tasks.py$36-41
Related to T2577