Bump lodash from 4.17.20 to 4.17.21 in /js

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.20 to 4.17.21.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](lodash/lodash@4.17.20...4.17.21)

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

Author: dependabot[bot]

js/package-lock.json

@@ -45,7 +45,7 @@
     "codemirror": "^5.54.0",
     "css-loader": "^3.6.0",
     "file-loader": "^6.0.0",
-    "lodash": "^4.17.20",
+    "lodash": "^4.17.21",
     "style-loader": "^1.2.1"
   },
   "jupyterlab": {