Bump lodash, gulp and gulp-copy

Bumps [lodash](https://github.com/lodash/lodash) to 4.17.21 and updates ancestor dependencies [lodash](https://github.com/lodash/lodash), [gulp](https://github.com/gulpjs/gulp) and [gulp-copy](https://github.com/klaascuvelier/gulp-copy). These dependencies need to be updated together.


Updates `lodash` from 4.17.4 to 4.17.21
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](lodash/lodash@4.17.4...4.17.21)

Updates `gulp` from 3.9.1 to 4.0.2
- [Release notes](https://github.com/gulpjs/gulp/releases)
- [Changelog](https://github.com/gulpjs/gulp/blob/master/CHANGELOG.md)
- [Commits](gulpjs/gulp@v3.9.1...v4.0.2)

Updates `gulp-copy` from 1.0.0 to 4.0.1
- [Release notes](https://github.com/klaascuvelier/gulp-copy/releases)
- [Changelog](https://github.com/klaascuvelier/gulp-copy/blob/master/CHANGELOG.md)
- [Commits](klaascuvelier/gulp-copy@1.0.0...4.0.1)

---
updated-dependencies:
- dependency-name: lodash
  dependency-type: indirect
- dependency-name: gulp
  dependency-type: direct:production
- dependency-name: gulp-copy
  dependency-type: direct:production
...

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