Bump lodash from 4.17.19 to 4.17.21 in /src/main/frontend

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.19 to 4.17.21.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](lodash/lodash@4.17.19...4.17.21)

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

Author: dependabot[bot]

Diff for: src/main/frontend/package-lock.json

@@ -10,7 +10,7 @@
     "handlebars": ">=4.7.7",
     "http-proxy-middleware": "^1.0.5",
     "kind-of": ">=6.0.3",
-    "lodash": ">=4.17.19",
+    "lodash": ">=4.17.21",
     "minimist": ">=0.2.1",
     "react": "^16.13.1",
     "react-dom": "^16.13.1",