[PHP] - Removes trailing comma from ::flattenArray()

Author: jtreminio

modules/openapi-generator/src/main/resources/php/ObjectSerializer.mustache

@@ -630,7 +630,7 @@ class ObjectSerializer
     private static function flattenArray(
         mixed $source,
         array &$destination,
-        string $start = '',
+        string $start = ''
     ) {
         $opt = [
             'prefix'          => '[',

samples/client/petstore/php/OpenAPIClient-php/lib/ObjectSerializer.php

@@ -639,7 +639,7 @@ public static function buildQuery(array $params, $encoding = PHP_QUERY_RFC3986):
     private static function flattenArray(
         mixed $source,
         array &$destination,
-        string $start = '',
+        string $start = ''
     ) {
         $opt = [
             'prefix'          => '[',

samples/client/petstore/php/psr-18/lib/ObjectSerializer.php

@@ -639,7 +639,7 @@ public static function buildQuery(array $params, $encoding = PHP_QUERY_RFC3986):
     private static function flattenArray(
         mixed $source,
         array &$destination,
-        string $start = '',
+        string $start = ''
     ) {
         $opt = [
             'prefix'          => '[',