Bump through2 from 2.0.5 to 4.0.2

Bumps [through2](https://github.com/rvagg/through2) from 2.0.5 to 4.0.2.
- [Commits](rvagg/through2@v2.0.5...v4.0.2)

---
updated-dependencies:
- dependency-name: through2
  dependency-version: 4.0.2
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

package-lock.json

@@ -24,7 +24,7 @@
   "dependencies": {
     "gulp-util": "^3.0.8",
     "htmlhint": "^1.1.4",
-    "through2": "^2.0.3"
+    "through2": "^4.0.2"
   },
   "devDependencies": {
     "gulp": "^4.0.2",