Update whatwg-fetch version to match the one in Gutenberg

[Hareesh Pillai]

Core currently has whatwg-fetch v3.0.0. Gutenberg has the latest version (v 3.6.2) in the ​package-lock.json file.

[SergeyBiryukov]

Introduced in [43719] / #45065.

[desrosj]

Related #53078.

I was trying to recall the reason why I did not include this update in #53078, but it's not coming to mind. It may have been an oversight. WordPress no longer depends on this polyfill as of [50934].

Based on the ​release notes, it seems updating this should be straightforward and will bring the latest update of the library to anyone still utilizing it.

Just a note for the contributor creating a patch for this: the version of the script needs to bumped in wp-includes/script-loader.php as well. The package is compiled into a script registered under the wp-polyfill-fetch handle.

[Hareesh Pillai]

Thanks for sharing the details, @desrosj.

WordPress no longer depends on this polyfill as of [50934].

In addition to updating, should we also remove this script from loading by default? Perhaps we could open a new ticket for that.

[desrosj]

The script should continue to be registered so that plugins and themes can enqueue the script if desired, but it should no longer be enqueued anywhere in WordPress Core. If it is, then we should fix that as it's a bug.

[rsiddharth]

Bump whatwg-fetch to version 3.6.2

[SergeyBiryukov]

In 51692:

External Libraries: Update whatwg-fetch package to version 3.6.2.

This matches the version used in the Gutenberg project.

While WordPress core no longer depends on this polyfill as of [50934], this brings the latest updates of the library to anyone still utilizing it.

For a full list of changes in this update, see the whatwg-fetch GitHub:
​https://github.com/github/fetch/compare/v3.0.0...v3.6.2

Follow-up to [43719], [50934].

Props hareesh-pillai, rsiddharth, desrosj.
Fixes #53929.