fix return datatype

Author: erikn69

src/Console/ModelsCommand.php

@@ -822,7 +822,7 @@ public function getPropertiesFromMethods($model)
                                     if ($this->write_model_relation_exists_properties) {
                                         $this->setProperty(
                                             Str::snake($method) . '_exists',
-                                            'int|null',
+                                            'bool|null',
                                             true,
                                             false
                                             // What kind of comments should be added to the relation count here?