pandoc: fix build by using buildDepends to match cabal file

The previously used dependency hsb2hs was a build-tools dependency,
but file-embed is build-depends:

https://github.com/jgm/pandoc/commit/ff991d1e2151479ff7dc15aba9c17251ff060408

Fixes #33349

pkgs/top-level/all-packages.nix

@@ -3896,7 +3896,7 @@ with pkgs;
 
   pandoc = haskell.lib.overrideCabal (haskell.lib.justStaticExecutables haskellPackages.pandoc) (drv: {
     configureFlags = drv.configureFlags or [] ++ ["-fembed_data_files"];
-    buildTools = drv.buildTools or [] ++ [haskellPackages.file-embed];
+    buildDepends = drv.buildDepends or [] ++ [haskellPackages.file-embed];
   });
 
   pamtester = callPackage ../tools/security/pamtester { };