Bump @types/node-fetch from 2.5.5 to 2.5.6 (#2631)

Bumps [@types/node-fetch](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/node-fetch) from 2.5.5 to 2.5.6.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/node-fetch)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

package-lock.json

@@ -53,7 +53,7 @@
     "@types/mocha": "~7.0.2",
     "@types/mock-fs": "~4.10.0",
     "@types/node": "~10.11.0",
-    "@types/node-fetch": "~2.5.5",
+    "@types/node-fetch": "~2.5.6",
     "@types/rewire": "~2.5.28",
     "@types/semver": "~7.1.0",
     "@types/sinon": "~9.0.0",