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]

Diff for: package-lock.json

@@ -22,7 +22,7 @@
     "gatsby-source-sanity": "^5.0.2",
     "gatsby-transformer-sharp": "^2.2.15",
     "get-youtube-id": "^1.0.1",
-    "lodash": "^4.17.15",
+    "lodash": "^4.17.21",
     "moment": "^2.24.0",
     "prop-types": "^15.7.2",
     "query-string": "^6.8.3",