About Page: Header images from previous release are cached

[ryelle]

When updating to 6.0 RC3 & viewing the About page, I still saw the old 5.9 image in the header. The image uses the same file name, so it must be locally cached.

This is similar to the issue raised in #55689, but the change on the welcome panel made that one invalid - the solution can be the same though, append the version to the background image URLs.

This appends the version to the header image URLs. It uses the major version only, since these images will not change in minor releases. This uses the same approach that was proposed in ​https://github.com/WordPress/wordpress-develop/pull/2686.

Trac ticket: https://core.trac.wordpress.org/ticket/55750

[peterwilsoncc]

In 53409:

Help/About: Ensure about page shows current header.

Add a query string parameter to the about page header images to ensure the cache is broken in browsers and CDNs.

Props ryelle.
Fixes #55750.

Merged in https://core.trac.wordpress.org/changeset/53409

[peterwilsoncc]

Reopening for merging to the 6.0 branch pending another committers review.

[audrasjb]

Alright the change looks good to me, this can be backported to branch 6.0.

[ryelle]

In 53412:

Help/About: Ensure about page shows current header.

Add a query string parameter to the about page header images to ensure the cache is broken in browsers and CDNs.

Props ryelle.
Merges [53409] to the 6.0 branch.
Fixes #55750.

[SergeyBiryukov]

In the future, would it make sense to create a build task for this, perhaps as part of grunt prerelease, so that we don't forget to bump the version here?