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>

package.json

@@ -32,7 +32,7 @@
     "joi-objectid": "~3.0.1",
     "jwt-simple": "^0.5.6",
     "kraken-js": "^2.3.0",
-    "lodash": "^4.17.15",
+    "lodash": "^4.17.21",
     "mongodb": "^3.6.2",
     "passport": "^0.4.1",
     "passport-jwt": "^4.0.0"