devel/interactive_rebase_tool: Update to 1.1.0

The license has been changed from ISCL to GPLv3+. See
https://github.com/MitMaro/git-interactive-rebase-tool/pull/116

Changes: https://github.com/MitMaro/git-interactive-rebase-tool/blob/master/CHANGELOG.md#110---2019-08-15
PR: 239949
Submitted by: petteri.valkonen@iki.fi (maintainer)