ipafont: make the font derivation fixed-output

- [x] make the font derivations fixed-output (https://github.com/NixOS/nixpkgs/issues/27754)

pkgs/data/fonts/ipafont/default.nix

@@ -1,23 +1,16 @@
-{ stdenv, fetchurl, unzip }:
+{ stdenv, fetchzip }:
 
-stdenv.mkDerivation {
+fetchzip {
   name = "ipafont-003.03";
 
-  src = fetchurl {
-    url = "http://ipafont.ipa.go.jp/old/ipafont/IPAfont00303.php";
-    sha256 = "f755ed79a4b8e715bed2f05a189172138aedf93db0f465b4e20c344a02766fe5";
-  };
+  url = "http://ipafont.ipa.go.jp/old/ipafont/IPAfont00303.php";
 
-  buildInputs = [ unzip ];
-
-  unpackPhase = ''
-    unzip $src
+  postFetch = ''
+    mkdir -p $out/share/fonts
+    unzip -j $downloadedFile \*.ttf -d $out/share/fonts/opentype
   '';
 
-  installPhase = ''
-    mkdir -p $out/share/fonts/opentype
-    cp ./IPAfont00303/*.ttf $out/share/fonts/opentype/
-  '';
+  sha256 = "0lrjd0bfy36f9j85m12afg5nvr5id3sig2nmzs5qifskbd7mqv9h";
 
   meta = {
     description = "Japanese font package with Mincho and Gothic fonts";