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] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -22,7 +22,7 @@
     "express": "~4.16.1",
     "http-errors": "~1.6.3",
     "jsonwebtoken": "^8.5.1",
-    "lodash": "^4.17.15",
+    "lodash": "^4.17.21",
     "mongoose": "^5.6.1",
     "morgan": "~1.9.1",
     "nodemailer": "^6.2.1",