qt: add fonts (#983)

Link: https://github.com/nix-community/stylix/pull/983

Reviewed-by: Kilian Mio <86004375+Mikilio@users.noreply.github.com>
Reviewed-by: NAHO <90870942+trueNAHO@users.noreply.github.com>

modules/qt/hm.nix

@@ -92,6 +92,11 @@
             ''
             + lib.optionalString (icons != null) ''
               icon_theme=${icons}
+            ''
+            + ''
+              [Fonts]
+              fixed="${config.stylix.fonts.monospace.name},${toString config.stylix.fonts.sizes.applications}"
+              general="${config.stylix.fonts.sansSerif.name},${toString config.stylix.fonts.sizes.applications}"
             '';
 
         in