Force revalidation headers when user logs out

Signed-off-by: snipe <snipe@snipe.net>

app/Http/Kernel.php

@@ -23,6 +23,7 @@ class Kernel extends HttpKernel
         \App\Http\Middleware\CheckForDebug::class,
         \Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,
         \App\Http\Middleware\SecurityHeaders::class,
+        \App\Http\Middleware\PreventBackHistory::class,
 
     ];