typstPackages: Do not build in Hydra

Downloading from the cache is basically the same
building anyways, no reason to build on Hydra TBH.

pkgs/by-name/ty/typst/build-universe-package.nix

@@ -45,6 +45,8 @@ lib.extendMkDerivation {
           RossSmyth
         ];
         license = lib.map (lib.flip lib.getAttr lib.licensesSpdx) license;
+        # Sending a bunch of trivial jobs to Hydra is not that great.
+        hydraPlatforms = [ ];
       }
       // lib.optionalAttrs (homepage != null) { inherit homepage; };
     };