Bump nth-check and gulp-image

Bumps [nth-check](https://github.com/fb55/nth-check) to 2.1.1 and updates ancestor dependency [gulp-image](https://github.com/1000ch/gulp-image). These dependencies need to be updated together.


Updates `nth-check` from 1.0.2 to 2.1.1
- [Release notes](https://github.com/fb55/nth-check/releases)
- [Commits](fb55/nth-check@v1.0.2...v2.1.1)

Updates `gulp-image` from 6.2.1 to 6.3.1
- [Release notes](https://github.com/1000ch/gulp-image/releases)
- [Commits](1000ch/gulp-image@v6.2.1...v6.3.1)

---
updated-dependencies:
- dependency-name: nth-check
  dependency-type: indirect
- dependency-name: gulp-image
  dependency-type: direct:development
...

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

Author: dependabot[bot]