chore(deps): bump lodash from 4.17.20 to 4.17.21 in /functions

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.20 to 4.17.21.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](https://github.com/lodash/lodash/compare/4.17.20...4.17.21)

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

functions/package-lock.json

@@ -1637,9 +1637,9 @@
       }
     },
     "lodash": {
-      "version": "4.17.20",
-      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.20.tgz",
-      "integrity": "sha512-PlhdFcillOINfeV7Ni6oF1TAEayyZBoZ8bcshTHqOYJYlrqzRK5hagpagky5o4HfCzzd1TRkXPMFq6cKk9rGmA=="
+      "version": "4.17.21",
+      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.21.tgz",
+      "integrity": "sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg=="
     },
     "lodash.camelcase": {
       "version": "4.3.0",