super-slicer-beta: 2.5.59.3 -> 2.5.59.6 (#283789)

Diff: https://github.com/supermerill/SuperSlicer/compare/2.5.59.3...2.5.59.6

pkgs/applications/misc/prusa-slicer/super-slicer.nix

···
       inherit patches;
     };
     beta = {
-      version = "2.5.59.3";
-      sha256 = "sha256-chHKEEMN0Dllebk7zQDg7mf2BU441RlSyXvXgiCmgA4=";
+      version = "2.5.59.6";
+      sha256 = "sha256-4ivhkcvVw5NlPsDz3J840aWc0qnp/XzCnTTCICwi3/c=";
       inherit patches;
     };
   };