Fixed wrong namespace on Devfalse driver

(cherry picked from commit 6b73b13)
Removed unused NS use

Author: Geolim4

src/phpFastCache/Drivers/Devfalse/Driver.php

@@ -12,10 +12,9 @@
  *
  */
 
-namespace phpFastCache\Drivers\Devnull;
+namespace phpFastCache\Drivers\Devfalse;
 
 use phpFastCache\Core\DriverAbstract;
-use phpFastCache\Core\StandardPsr6StructureTrait;
 use phpFastCache\Entities\driverStatistic;
 use phpFastCache\Exceptions\phpFastCacheDriverCheckException;
 use phpFastCache\Exceptions\phpFastCacheDriverException;