- Add custom build backend which overrides certain hooks
- Include custom build backend in sdists via `MANIFEST.in`
- Remove `build>=1.0.0` workaround from `build-and-sign.sh`
- Add build backend tests, update order of tests and coverage config
The "patch" status which was added by fba55ae also accidentally added
annotations. These are annoying when lots of new and uncovered lines get
added, and it makes reading and reviewing the PR diff unnecessarily
difficult. We are only interested in the "patch" status check itself.
https://docs.codecov.io/docs/github-checks-beta
* ci.coverage: enable branch coverage
* ci.coverage: gather coverage from tests as well
* ci.codecov: turn codecov config into a dotfile
* ci.codecov: disable comment, split reports by path
* ci.codecov: require all reports before notifying