Bump gulp-strip-debug from 4.0.0 to 6.0.0

Bumps [gulp-strip-debug](https://github.com/sindresorhus/gulp-strip-debug) from 4.0.0 to 6.0.0.
- [Release notes](https://github.com/sindresorhus/gulp-strip-debug/releases)
- [Commits](sindresorhus/gulp-strip-debug@v4.0.0...v6.0.0)

---
updated-dependencies:
- dependency-name: gulp-strip-debug
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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