[stringzilla] update to 5.1.1

[toge (toge)]

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version, or no changes were necessary.
• Any fixed CI baseline and CI feature baseline entries are removed from that file, or no entries needed to be changed.
• All patch files in the port are applied and succeed.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Exactly one version is added in each modified versions file.

https://github.com/ashvardanian/StringZilla/releases/tag/v5.1.1

[Billy O'Neal (BillyONeal)]

GPT 5.6 Sol notes:

The recursive include copy in ports/stringzilla/portfile.cmake installs include/stringzillas, although upstream documents StringZillas as a compiled, separate package. Those C++ headers require forkunion.h, and the C API requires libraries that this port does not install. This predates the PR and does not block the version update, but a follow-up should either omit include/stringzillas from this header-only port or package its dependencies and compiled libraries.

Thanks for the update!