feat: Add diff.mtex.dev to configuration. Also: fix the version in config.php

Author: Michaelninder

config.php

@@ -1,7 +1,7 @@
 <?php
 
 return [
-    'version' => 'v1.2.5',
+    'version' => 'v1.3.1',
     'services' => [
         [
             'address' => 'https://mtex.dev',
@@ -31,6 +31,13 @@
             'github' => 'https://github.com/MTEDdotDev/nx.mtex.dev',
             'is_deployed' => true,
         ],
+        [
+            'address' => 'https://diff.mtex.dev',
+            'name' => 'MTEX Diff',
+            'description' => 'A visual comparison tool for JSON payloads and code.',
+            'github' => 'https://github.com/MTEDdotDev/diff.mtex.dev',
+            'is_deployed' => true,
+        ],
         [
             'address' => 'https://gimy.site',
             'name' => 'GimySite',