Bump lodash from 4.17.4 to 4.17.21 in /boilerplate

Bumps [lodash](https://github.com/lodash/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)

---
updated-dependencies:
- dependency-name: lodash
  dependency-type: direct:development
...

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

boilerplate/package.json

@@ -28,7 +28,7 @@
     "json-loader": "0.5.4",
     "less": "2.7.1",
     "less-loader": "4.0.5",
-    "lodash": "4.17.4",
+    "lodash": "4.17.21",
     "postcss-loader": "2.0.6",
     "run-sequence": "2.1.0",
     "through2": "2.0.1",