修复代码生成器无法取消选中timestamps参数bug

src/Scaffold/FormCreator.php

@@ -15,7 +15,7 @@ trait FormCreator
     {
         $primaryKey = $primaryKey ?: request('primary_key', 'id');
         $fields = $fields ?: request('fields', []);
-        $timestamps = $timestamps === null ? request('timestamps', true) : $timestamps;
+        $timestamps = $timestamps === null ? request('timestamps') : $timestamps;
 
         $rows = [
             <<<EOF

src/Scaffold/GridCreator.php

@@ -14,7 +14,7 @@ trait GridCreator
     {
         $primaryKey = $primaryKey ?: request('primary_key', 'id');
         $fields = $fields ?: request('fields', []);
-        $timestamps = $timestamps === null ? request('timestamps', true) : $timestamps;
+        $timestamps = $timestamps === null ? request('timestamps') : $timestamps;
 
         $rows = [
             "\$grid->{$primaryKey}->bold()->sortable();",

src/Scaffold/ShowCreator.php

@@ -14,7 +14,7 @@ trait ShowCreator
     {
         $primaryKey = $primaryKey ?: request('primary_key', 'id');
         $fields = $fields ?: request('fields', []);
-        $timestamps = $timestamps === null ? request('timestamps', true) : $timestamps;
+        $timestamps = $timestamps === null ? request('timestamps') : $timestamps;
 
         $rows = [];