php.extensions.xdebug: update src attribute

So it can be automatically updated with `nix-update`

pkgs/development/php-packages/xdebug/default.nix

@@ -1,10 +1,18 @@
-{ buildPecl, lib }:
+{ buildPecl, lib, fetchFromGitHub }:
+
+let
+  version = "3.2.0";
+in buildPecl {
+  inherit version;
 
-buildPecl {
   pname = "xdebug";
 
-  version = "3.2.0";
-  sha256 = "1drj00z8ididm2iw7a7pnrsvakrr1g0i49aqkyz5zpysxh7b4sbp";
+  src = fetchFromGitHub {
+    owner = "xdebug";
+    repo = "xdebug";
+    rev = version;
+    sha256 = "sha256-GQB69aETp8STyT4GHQQSPJBVEynWifbmGQXUeISvLRI=";
+  };
 
   doCheck = true;
   checkTarget = "test";
@@ -12,6 +20,7 @@ buildPecl {
   zendExtension = true;
 
   meta = with lib; {
+    changelog = "https://github.com/xdebug/xdebug/releases/tag/${version}";
     description = "Provides functions for function traces and profiling";
     license = licenses.php301;
     homepage = "https://xdebug.org/";