fix(gulp-sharp): load yoctocolors as a runtime dependency instead of bundling it

[panz3r]

yoctocolors was a devDependency bundled into dist by rollup, so its updates could only reach users through a new gulp-sharp release, and Dependabot would label them chore(deps-dev).

• Mark it external in the rollup build, like sharp here and browser-sync in gulp-browser-sync.
• Declare it in dependencies (^2.2.0).

Built output now imports yoctocolors instead of inlining it. This will cut gulp-sharp 1.0.3.

Merge before the lockfile security PR, which touches the same lines.