Update SubtitleComposer download location

Subtitle Composer app info is outdated and download link is wrong/old.

* Link to the original application project's (upstream) download page from where AppImage can be downloaded: https://subtitlecomposer.kde.org/download.html
* Link to the most recent AppImage (stable) for x86_64: https://downloadcontent.opensuse.org/repositories/home:/maxrd2/AppImage/subtitlecomposer-latest-x86_64.AppImage
* Link to the most recent AppImage (git) for x86_64: https://downloadcontent.opensuse.org/repositories/home:/maxrd2/AppImage/subtitlecomposer-git-latest-x86_64.AppImage
* Link to the most recent AppImage (stable) for i686: https://downloadcontent.opensuse.org/repositories/home:/maxrd2/AppImage/subtitlecomposer-latest-i686.AppImage
* Link to the most recent AppImage (git) for i686 https://downloadcontent.opensuse.org/repositories/home:/maxrd2/AppImage/subtitlecomposer-git-latest-i686.AppImage
* Link to the most recent AppImage (stable) for aarch64: https://downloadcontent.opensuse.org/repositories/home:/maxrd2/AppImage/subtitlecomposer-latest-aarch64.AppImage
* Link to the most recent AppImage (git) for aarch64 https://downloadcontent.opensuse.org/repositories/home:/maxrd2/AppImage/subtitlecomposer-git-latest-aarch64.AppImage
* Link to the most recent AppImage (stable) for armv7l: https://downloadcontent.opensuse.org/repositories/home:/maxrd2/AppImage/subtitlecomposer-latest-armv7l.AppImage
* Link to the most recent AppImage (git) for armv7l https://downloadcontent.opensuse.org/repositories/home:/maxrd2/AppImage/subtitlecomposer-git-latest-armv7l.AppImage

AppImageHub page: https://appimage.github.io/Subtitle_Composer/