fix: remove unneeded cast()

Author: kenjis

system/Database/Postgre/Builder.php

@@ -579,11 +579,7 @@ static function ($key, $value) use ($table, $alias, $that) {
                                 );
                         }
 
-                        return $table . '.' . $value . ' = '
-                            . $that->cast(
-                                $alias . '.' . $value,
-                                $that->getFieldType($table, $key)
-                            );
+                        return $table . '.' . $value . ' = ' . $alias . '.' . $value;
                     },
                     array_keys($constraints),
                     $constraints