chore: revert direct version changes to let release-it handle versioning

Author: jimmyn

build/openapitools.json

@@ -11,7 +11,7 @@
         "removeOperationIdPrefix": true,
         "additionalProperties": {
           "packageName": "MONEI-PHP-SDK",
-          "artifactVersion": "2.6.0",
+          "artifactVersion": "2.5.1",
           "gitHost": "github.com",
           "gitUserId": "monei",
           "gitRepoId": "monei-php-sdk"
@@ -24,7 +24,7 @@
         "removeOperationIdPrefix": true,
         "additionalProperties": {
           "packageName": "MONEI-PHP-SDK",
-          "artifactVersion": "2.6.0",
+          "artifactVersion": "2.5.1",
           "gitHost": "github.com",
           "gitUserId": "monei",
           "gitRepoId": "monei-php-sdk"

lib/MoneiClient.php

@@ -37,7 +37,7 @@ class MoneiClient
     /**
      * @var string
      */
-    public const SDK_VERSION = '2.6.0';
+    public const SDK_VERSION = '2.5.1';
 
     /**
      * @var string