community/zeal: change source to release's git tag archive

The release archives posted on github include a zeal.desktop file with the wrong line endings, reported upstream here: https://github.com/zealdocs/zeal/issues/1610

Switching the source archive to the release's git tag avoids the this problem since it builds from what's in the git repo at that tag. The file has the correct line endings in the git repo, it's only the release source archive where this is wrong.