SSH-Key Strength

## Expected behavior
It should be possible to setup a SSH-Key strength.
In Gitlab I use at least 4096 Bit Key's.

## Actual behavior

*A generated SSH-Key has a strength of 2048 B.*

## Steps to reproduce

*Add Project.*

*src/PHPCensor/Helper/SshKey.php*

```php
$output = @shell_exec('ssh-keygen -t rsa -b 2048 -f '.$keyFile.' -N "" -C "deploy@php-censor"');
```

