Configure codecov project and patch status settings (#1077)
Configure codecov project and patch status settings (#1077)

- Set the project coverage target to "auto", i.e., coverage in PRs must increase compared to the base branch, but allow 0.25% drop
- Set the patch coverage target to 90%
- Remove the undocumented configuration `if_no_uploads`

References:

- https://docs.codecov.io/docs/common-recipe-list
- https://docs.codecov.io/docs/commit-status
GenericMappingTools/gmt-python,GenericMappingTools/gmt-python