zstd: update to 1.5.7

[mvwieringen]

No description provided.

[citrus-it]

According to the release notes:

edit: man pages were not properly updated in this package, and are still pointing to v1.5.6. If you want the v1.5.7 version, they are updated in dev branch, and can be cherry-picked using commit facebook/zstd@6af3842. Alternatively, they can also be built locally using make manual and make -C programs man.

So we might want to check and perhaps do one of those to ship the correct pages.

[citrus-it]

Thanks @mvwieringen. I don't know why they just didn't publish a new release instead of updating the release notes.