Since we're not running tests or other things that are more sensitive to
changes in the VM environment, use ubuntu-latest to avoid the busy work
of updating the VM image.
GH workflows aren't allowed to trigger other GH workflows. Since
commitlint is a required check now, we need something manual to happen
for it to run on vim-patch/api-doc PRs.
Creating these PRs as drafts and then marking them as "ready to review"
when we want to merge them will provide the manual trigger to run
commitlint.
[skip ci]
