remove lines between use statements

                    
|Q            |A   |
|---          |--- |
|Bug Fix?     |#575|
|New Feature? |n   |
|BC Breaks?   |n   |
|Deprecations?|n   |
|Tests Pass?  |n   |
|Fixed Tickets|    |
|License      |MIT |
|Doc PR       |    |
                    


 Sent using [Gush](https://github.com/gushphp/gush)
The final form of `fix` method should be only sth like:
```php
$tokens = Tokens::fromCode($content);
$this->removeOneLineBreakBetweenUseStatements($tokens);

return $tokens->generateCode();
```