Support '/' as a possible column name. (#45268)

Escape '/' when checking for guard-able column.

Author: amanpatel

src/Illuminate/Database/Eloquent/Concerns/GuardsAttributes.php

@@ -202,7 +202,7 @@ public function isGuarded($key)
         }
 
         return $this->getGuarded() == ['*'] ||
-               ! empty(preg_grep('/^'.preg_quote($key).'$/i', $this->getGuarded())) ||
+               ! empty(preg_grep('/^'.preg_quote($key, '/').'$/i', $this->getGuarded())) ||
                ! $this->isGuardableColumn($key);
     }