Bumps [retain_mut](https://github.com/upsuper/retain_mut) from 0.1.1 to 0.1.2.
- [Release notes](https://github.com/upsuper/retain_mut/releases)
- [Commits](https://github.com/upsuper/retain_mut/compare/v0.1.1...v0.1.2)

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>