Bump gdk-pixbuf from 0.17.10 to 0.18.5

Bumps [gdk-pixbuf](https://github.com/gtk-rs/gtk-rs-core) from 0.17.10 to 0.18.5.
- [Release notes](https://github.com/gtk-rs/gtk-rs-core/releases)
- [Changelog](https://github.com/gtk-rs/gtk-rs-core/blob/master/CHANGELOG.md)
- [Commits](gtk-rs/gtk-rs-core@0.17.10...0.18.5)

---
updated-dependencies:
- dependency-name: gdk-pixbuf
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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