Bump gulp-sourcemaps from 2.6.5 to 3.0.0

Bumps [gulp-sourcemaps](https://github.com/gulp-sourcemaps/gulp-sourcemaps) from 2.6.5 to 3.0.0.
- [Release notes](https://github.com/gulp-sourcemaps/gulp-sourcemaps/releases)
- [Commits](gulp-sourcemaps/gulp-sourcemaps@v2.6.5...v3.0.0)

---
updated-dependencies:
- dependency-name: gulp-sourcemaps
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -53,7 +53,7 @@
     "gulp-istanbul": "^1.1.3",
     "gulp-jasmine": "^4.0.0",
     "gulp-load-plugins": "^1.6.0",
-    "gulp-sourcemaps": "^2.6.5",
+    "gulp-sourcemaps": "^3.0.0",
     "gulp-uglify": "^3.0.2",
     "gulp-util": "^3.0.8",
     "handlebars": "^4.7.7",