Bump facade/ignition from 1.16.4 to 1.16.15

Bumps [facade/ignition](https://github.com/facade/ignition) from 1.16.4 to 1.16.15.
- [Release notes](https://github.com/facade/ignition/releases)
- [Changelog](https://github.com/facade/ignition/blob/master/CHANGELOG.md)
- [Commits](https://github.com/facade/ignition/compare/1.16.4...1.16.15)
Signed-off-by: dependabot[bot] <support@github.com>