Your build.zig.zon uses a branch specific url, this mean that the upstream project breaks your build when it updates its branch (because then the hashes no longer match).
To avoid that use the git+https protocol which automatically creates commit specific urls because it automatically adds the commit hash as the fragment/hash/# part of the url, or manually get a commit specific url like described here: Best way to release packages for libraries? - #2 by Sze, the changing the ending to tar is no longer necessary.