ci: add dependabot config

See merge request !1

Bumps [github.com/sanity-io/litter](https://github.com/sanity-io/litter) from 1.3.0 to 1.5.1.
- [Release notes](https://github.com/sanity-io/litter/releases)
- [Changelog](https://github.com/sanity-io/litter/blob/main/CHANGELOG.md)
- [Commits](https://github.com/sanity-io/litter/compare/v1.3.0...v1.5.1)

chore(deps): bump github.com/sanity-io/litter from 1.3.0 to 1.5.1

See merge request !2

ci: change to codecov binary instead of bash uploader

See merge request !3

Bumps [github.com/sanity-io/litter](https://github.com/sanity-io/litter) from 1.5.1 to 1.5.2.
- [Release notes](https://github.com/sanity-io/litter/releases)
- [Changelog](https://github.com/sanity-io/litter/blob/main/CHANGELOG.md)
- [Commits](https://github.com/sanity-io/litter/compare/v1.5.1...v1.5.2)

chore(deps): bump github.com/sanity-io/litter from 1.5.1 to 1.5.2

See merge request !4

Bumps [github.com/sanity-io/litter](https://github.com/sanity-io/litter) from 1.5.2 to 1.5.4.
- [Release notes](https://github.com/sanity-io/litter/releases)
- [Changelog](https://github.com/sanity-io/litter/blob/main/CHANGELOG.md)
- [Commits](https://github.com/sanity-io/litter/compare/v1.5.2...v1.5.4)

chore(deps): bump github.com/sanity-io/litter from 1.5.2 to 1.5.4

See merge request !5

Bumps [github.com/sanity-io/litter](https://github.com/sanity-io/litter) from 1.5.4 to 1.5.5.
- [Release notes](https://github.com/sanity-io/litter/releases)
- [Changelog](https://github.com/sanity-io/litter/blob/main/CHANGELOG.md)
- [Commits](https://github.com/sanity-io/litter/compare/v1.5.4...v1.5.5)

chore(deps): bump github.com/sanity-io/litter from 1.5.4 to 1.5.5

See merge request !6