Update repository url in package.json

[irekrog]

:warning: Make sure you are targeting microsoft/react-native-macos for your PR :warning:

(then delete these lines)

Please select one of the following

• [ ] I am removing an existing difference between facebook/react-native and microsoft/react-native-macos :thumbsup:
• [ ] I am cherry-picking a change from Facebook's react-native into microsoft/react-native-macos :thumbsup:
• [ ] I am making a fix / change for the macOS implementation of react-native
• [ ] I am making a change required for Microsoft usage of react-native

Summary:

Changelog:

Test Plan:

[irekrog]

duplicates https://github.com/microsoft/react-native-macos/pull/2005