Release 9.4.0

[kelson42]

• Secure the CI is green on git main
• Check if minimal versions of library dependences is properly given in Meson
• Update subprojects with appropriate library dependence versions (like in kiwix-build)
• If major version deb package has to be updated
• Kiwix-Build is OK
• Update the Changelog
• Update version
• Close current milestone and create new one incrementally (a priori a minor version)
• Create a tag on git
• Ensure new sources/binaries are published on https://download.openzim.org/release/libzim/
• Update the Github release with the Changelog
• Check Homebrew package
• Check if release has been a success on PPA
• Create new empty entry in Changelog (placeholder for future entries)
• Publicize these new versions