iosevka-bin: Fix meta attributes

Joining the entire `iosevka.meta` set seemed to cause some attributes to
not be set as expected. For example `iosevka-bin.meta.name` was
`iosevka-14.0.1` instead of `iosevka-bin-10.1.0`, and
`iosevka-bin.meta.position` also pointed to `iosevka/default.nix`
instead of `iosevka/bin.nix`.

pkgs/data/fonts/iosevka/bin.nix

@@ -30,7 +30,8 @@ in stdenv.mkDerivation rec {
     unzip -d $out/share/fonts/truetype $src
   '';
 
-  meta = iosevka.meta // {
+  meta = {
+    inherit (iosevka.meta) homepage downloadPage description license platforms;
     maintainers = with lib.maintainers; [
       cstrahan
     ];