Added Winnie and Martin. Corrected github account for Maxwell. (Schmi…

…edmayerLab#32)

# *Name of the PR*

## ♻️ Current situation & Problem
* GitHub username for Maxwell was wrong
* Winnie and Martin were missing


## ⚙️ Release Notes
* Corrected Maxwell's GitHub username
* Added Winnie and Martin


## 📚 Documentation
*Please ensure that you properly document any additions in conformance
to [Spezi Documentation
Guide](https://github.com/StanfordSpezi/.github/blob/main/DOCUMENTATIONGUIDE.md).*
*You can use this section to describe your solution, but we encourage
contributors to document your reasoning and changes using in-line
documentation.*


## ✅ Testing
*Please ensure that the PR meets the testing requirements set by CodeCov
and that new functionality is appropriately tested.*
*This section describes important information about the tests and why
some elements might not be testable.*


### Code of Conduct & Contributing Guidelines
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[Code of
Conduct](https://github.com/StanfordBDHG/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordBDHG/.github/blob/main/CONTRIBUTING.md):
- [ x ] I agree to follow the [Code of
Conduct](https://github.com/StanfordBDHG/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordBDHG/.github/blob/main/CONTRIBUTING.md).