[BUGFIX] Add namespace declaration for command

The namespace declaration for command was missing, leading to an undefined
constant. This is fixed now.

Resolves: #746
Signed-off-by: Marcus Schwemer <marcus.schwemer@in2code.de>

Author: mschwemer

Classes/Command/CleanupUploadsCommand.php

@@ -2,6 +2,7 @@
 declare(strict_types = 1);
 namespace In2code\Powermail\Command;
 
+use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;