Fixes test error:
```
>> Problem: [http_splitting] Possible HTTP-Splitting vulnerability.
Description: Using variables that can contain "\n" or "\r" may lead to http injection.
```
Summary: `$uri` should never be used in `return` statements.
See: https://github.com/yandex/gixy/blob/master/docs/en/plugins/httpsplitting.md
In this case, `$uri` always equals `/`, so just replace it.
eec82e1bf9