Add void type to MainCommand::configure

Fixes
```
  1x: Method "Symfony\Component\Console\Command\Command::configure()" might add "void" as a native return type declaration in the future. Do the same in child class "Sentry\SentryBundle\Tests\End2End\App\Command\MainCommand" now to avoid errors or add an explicit @return annotation to suppress this message.
```

tests/End2End/App/Command/MainCommand.php

@@ -11,7 +11,7 @@
 
 class MainCommand extends Command
 {
-    protected function configure()
+    protected function configure(): void
     {
         $this
             ->addOption('option1', null, InputOption::VALUE_NONE)