Allow to backup databases that are not in config

[applyACS]

If I try to run the command only for database but for one that is not in config (backup.source.databases) I get an error that "There are no files to be backed up."

Here is an example:

the command I try to run

php artisan backup:run --only-db --db-name=db3

the config file

'databases' => [
                'db1',
                'db2'
            ],

[angeljqv]

Feel free to make a PR for that