metainfo: Correct release type
It's 'development', not 'unstable', which the appstream uses. https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#tag-releases
It's 'development', not 'unstable', which the appstream uses. https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#tag-releases