gcr_4: Switch to new version policy

It uses SemVer with `micro >= 90` being considered unstable.

https://gitlab.gnome.org/GNOME/gcr/-/tree/4.3.90.3#versions

pkgs/development/libraries/gcr/4.nix

@@ -38,7 +38,7 @@ stdenv.mkDerivation rec {
   ];
 
   src = fetchurl {
-    url = "mirror://gnome/sources/${pname}/${lib.versions.majorMinor version}/${pname}-${version}.tar.xz";
+    url = "mirror://gnome/sources/gcr/${lib.versions.majorMinor version}/gcr-${version}.tar.xz";
     hash = "sha256-w+6HKOQ2SwOX9DX6IPkvkBqxOdKyZPTgWdZ7PA9DzTY=";
   };
 
@@ -103,7 +103,8 @@ stdenv.mkDerivation rec {
   passthru = {
     updateScript = gnome.updateScript {
       attrPath = "gcr_4";
-      packageName = pname;
+      packageName = "gcr";
+      versionPolicy = "ninety-micro-unstable";
     };
   };