typstPackages: skip unpack phase

Some typst packages include a Makefile for unit tests, which break the
builds.
Since typst packages are just static files no attempt should be made to
build them.

pkgs/build-support/build-typst-package.nix

@@ -40,6 +40,8 @@ lib.extendMkDerivation {
     {
       name = "typst-package-${finalAttrs.pname}-${finalAttrs.version}";
 
+      dontUnpack = true;
+
       installPhase =
         let
           outDir = "$out/lib/typst-packages/${finalAttrs.pname}/${finalAttrs.version}";