[php-nextgen]: Simplify enum type (OpenAPITools#23320)

Co-authored-by: coffeemakr <coffeemakr@users.noreply.github.com>

Author: coffeemakr

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpNextgenClientCodegen.java

@@ -167,16 +167,6 @@ private ModelsMap postProcessModelsMap(ModelsMap objs) {
 
                 prop.vendorExtensions.putIfAbsent("x-php-prop-type", propType);
             }
-
-            if (model.isEnum) {
-                for (Map<String, Object> enumVars : (List<Map<String, Object>>) model.getAllowableValues().get("enumVars")) {
-                    if ((Boolean) enumVars.get("isString")) {
-                        model.vendorExtensions.putIfAbsent("x-php-enum-type", "string");
-                    } else {
-                        model.vendorExtensions.putIfAbsent("x-php-enum-type", "int");
-                    }
-                }
-            }
         }
         return objs;
     }

modules/openapi-generator/src/main/resources/php-nextgen/model_enum.mustache

@@ -1,4 +1,4 @@
-enum {{classname}}: {{exts.x-php-enum-type}}
+enum {{classname}}: {{dataType}}
 {
     {{#allowableValues}}
     {{#enumVars}}