fixes unknown exception class

[maglnet]

When a path is not existing/readable and laminas/laminas-db is not required within the project, the following error came up in my project:

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   The application has thrown an exception!
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 Error
 Class 'Zend\Db\TableGateway\Exception\RuntimeException' not found
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Imho this is just an automatically created use statement that should point to the RuntimeException class provided by this package