Certain syntaxes in ruby cause extraction errors

The following ruby code causes an extraction error when parsed.

```ruby
def foo(bar: nil) = raise NotImplementedError
```

The error message is as follows.

```
Error: Extraction failed in [filepath] with error A parse error occurred. Check the syntax of the file. If the file is invalid, correct the error or exclude the file from analysis.
```

This code is correct ruby syntax.
This problem was reproduced with CodeQL version 2.4.5.