Bump lodash from 4.17.15 to 4.17.21 in /zeppelin-web-angular (#4689)

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.15 to 4.17.21.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](lodash/lodash@4.17.15...4.17.21)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

zeppelin-web-angular/package.json

@@ -34,7 +34,7 @@
     "diff-match-patch": "^1.0.4",
     "github-markdown-css": "^3.0.1",
     "highlight.js": "^9.15.8",
-    "lodash": "^4.17.11",
+    "lodash": "^4.17.21",
     "mathjax": "2.7.5",
     "monaco-editor": "0.15.1",
     "ng-zorro-antd": "^8.4.0",