Bump through2 from 4.0.2 to 5.0.3

Bumps [through2](https://github.com/rvagg/through2) from 4.0.2 to 5.0.3.
- [Release notes](https://github.com/rvagg/through2/releases)
- [Changelog](https://github.com/rvagg/through2/blob/master/CHANGELOG.md)
- [Commits](rvagg/through2@v4.0.2...v5.0.3)

---
updated-dependencies:
- dependency-name: through2
  dependency-version: 5.0.3
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

package.json

@@ -26,7 +26,7 @@
     "acorn-node": "^2.0.1",
     "dash-ast": "^2.0.1",
     "multisplice": "^1.0.0",
-    "through2": "^4.0.2"
+    "through2": "^5.0.3"
   },
   "keywords": [
     "environment",