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

@@ -68,7 +68,7 @@
     "fs-extra": "4.0.3",
     "jest": "24.9.0",
     "jest-transform-stub": "2.0.0",
-    "lodash": "4.17.15",
+    "lodash": "4.17.21",
     "prettier": "1.18.2",
     "react": "16.8.6",
     "react-addons-test-utils": "15.6.2",