ITK v5.4.0 has been tagged! 
We have a new release-5.4 branch. 
Patches intended for future 5.4 patch releases (5.4.1, etc) should be branched from here and a pull-request created against this branch:
Branch from release-5.4:
git checkout release-5.4
git checkout -b new_patch_for_5.4
# hack hack
git commit -m 'COMP: Fix warning for ...'
git push phcerdan
Open PR against the upstream release-5.4 branch
Once the commit is in your fork of ITK, open a pull-request and manually choose the release-5.4 branch.
The actual release of 5.4.0 will be announced shortly 