chore: update submodules, github actions, macOS runners

[romeoahmed]

Submodules:

• lz4: 5ff8396 -> 5c4c1fb
• nanopass: f3100ce -> bb47b56
• stex: 5e4f0ca -> afa6075
• zlib: da607da -> 09a1572
• zuo: 063f82c -> a288cbf

GitHub Actions:

• actions/checkout: v4 -> v6
• actions/upload-artifact: v4 -> v7

Runner Images:

• macos-15 -> macos-26
• macos-15-intel -> macos-26-intel

[burgerrg]

Thank you for the updates. I would like to use released versions of software whenever possible.

• lz4: could be updated to v1.10.0
• nanopass: @akeep, is the latest ready for release?
• stex: @dybvig, is the latest ready for release?
• zlib: currently at the latest release, v1.3.2
• zuo: @mflatt, is the proposed update ready for Chez Scheme?

[romeoahmed]

Thanks for reviewing. However, I noticed that the latest commit to zlib is a critical bug fix and has passed all CI/CD tests, so I think the develop branch is worthwhile.
Fixed the inflateBack() bug that would fail to detect a too-far back

[burgerrg]

I'm sure it won't take the zlib team long to cut an official release.