Update yargs interface usage

[christian-bromann]

Proposed changes

Updating the eslint parser has caused code in the cli to break as it couldn't find the property _ in the yargs argv object anymore. My assumption is that we haven't updated the way we use yargs in a while and interfaces have changed that discourage the usage of this property. I have updated it which caused the type issues to go away.

According to the yargs docs:

Calling .parse() with no arguments is equivalent to calling .argv

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Checklist

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• I have added proper type definitions for new commands (if appropriate)

Further comments

n/a

Reviewers: @webdriverio/project-committers