Tags/Return: remove redundant condition

Psalm flags this condition as redundant:
```
ERROR: RedundantCondition - src/DocBlock/Tags/Return_.php:62:48 - "" can never contain non-empty-lowercase-string (see https://psalm.dev/122)
        return $type . ($description !== '' ? ($type !== '' ? ' ' : '') . $description : '');
```

Based on the statement in the line above - `$type = $this->type ? '' . $this->type : 'mixed';` -, Psalm is correct and the `$type` variable can never be an empty string.

Author: jrfnl

src/DocBlock/Tags/Return_.php

@@ -59,6 +59,6 @@ public function __toString(): string
 
         $type = $this->type ? '' . $this->type : 'mixed';
 
-        return $type . ($description !== '' ? ($type !== '' ? ' ' : '') . $description : '');
+        return $type . ($description !== '' ? ' ' . $description : '');
     }
 }