Bump lodash from 4.17.15 to 4.17.21

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)

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

Author: dependabot[bot]

package-lock.json

@@ -35,7 +35,7 @@
     "iconv": "^2.3.0",
     "jsonwebtoken": "^8.1.0",
 
-    "lodash": "^4.17.15",
+    "lodash": "^4.17.21",
     "mongodb": "^3.5.0",
     "mongoose": "^5.8.7",
     "morgan": "^1.9.1",