Summary

As title pointed, this repo is licensed with MIT License, but the Additional Restriction Clause statement inside the file violates the term of MIT License.
The maintainers of this repository should fix this issue as soon as possible.

Details

This issue is referring to the commit 0e1a91b and commit 2b04342

Let's take a look at MIT License:

MIT License Template (link)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software
...

MIT License template has stated that if you licensed with MIT License, any person is granted, free of charge to obtaining a copy of this software and associated documentation files, including to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software.
Therefore, stating restriction inside MIT License is not only invalid on legal means, also violates the term of MIT License.

If you cannot fully understand the means of MIT License document, you can refer to the attachment below.

Also, the terms of contributing should be stated in separate CONTRIBUTING.md file.

Attachment

• The summary of MIT License from GitHub