[bxzstr] Update to 1.2.1

[Cheney-W]

Update bxzstr to the latest version 1.2.1.

• [x] Changes comply with the maintainer guide.
• [x] SHA512s are updated for each updated download.
• [ ] ~The "supports" clause reflects platforms that may be fixed by this new version.~
• [ ] ~Any fixed CI baseline entries are removed from that file.~
• [ ] ~Any patches that are no longer applied are deleted from the port's directory.~
• [x] The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• [x] Only one version is added to each modified port's versions file.