@mthom, I see that you prefer to make big changes on a separate long-term development branch, and then periodically merge it into master. I think this is fine and you should develop however you like. But unfortunately this workflow doesn't work with the CI system very well, so CI won't help you catch issues like the one above where bumping rug to 1.19 requires changing scryer's MSRV to 1.65 mentioned above.

Maybe consider opening a PR to merge the working branch into master, and just leave it there while you work. (Mark it as draft or wip if you want to communicate that status.) That would trigger the CI build to run whenever you push changes which would give you a pulse on how your changes would affect the builds and tests across the target supported environments.

thanks @infogulch, I'll do that from now on.