Bump node-fetch from 2.6.0 to 2.6.7 in /gatsby-source-ac

Bumps [node-fetch](https://github.com/node-fetch/node-fetch) from 2.6.0 to 2.6.7.
- [Release notes](https://github.com/node-fetch/node-fetch/releases)
- [Commits](node-fetch/node-fetch@v2.6.0...v2.6.7)

---
updated-dependencies:
- dependency-name: node-fetch
  dependency-type: direct:production
...

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

Author: dependabot[bot]

gatsby-source-ac/package-lock.json

@@ -10,6 +10,6 @@
   "license": "ISC",
   "dependencies": {
     "cli-progress": "^3.8.2",
-    "node-fetch": "^2.6.0"
+    "node-fetch": "^2.6.7"
   }
 }