pympress: Move gobject-introspection to nativeBuildInputs

- Previously the software would fail to run with an error showing that
  it couldn't find gobject-introspection typelib files for GTK3
- By adding gobject-introspection to nativeBuildInputs, the gi typelib
  path is set so that we have all of the typelibs we need

Co-authored-by: Skyler Grey <skyler3665@gmail.com>

pkgs/applications/office/pympress/default.nix

@@ -21,11 +21,11 @@ python3Packages.buildPythonApplication rec {
 
   nativeBuildInputs = [
     wrapGAppsHook
+    gobject-introspection
   ];
 
   buildInputs = [
     gtk3
-    gobject-introspection
     poppler_gi
   ] ++ lib.optional withGstreamer libcanberra-gtk3;