It looks like WordPress.CodeAnalysis.AssignmentInCondition.Found has been renamed upstream and is now Generic.CodeAnalysis.AssignmentInCondition.FoundInWhileCondition

I don't believe this repo actually does an assignment inside of a while condition at the moment -- which is why there weren't any test failures when updating to WPCS 3.0.

I had one of these in a local wp-cli project and when searching for the origin of that exclude I realized that it had been copied from the phpcs.xml file in this repo which I used as a starting point.

While I was here I also removed the PSR2 rule below it based on the comment suggesting it should be removed once PHPCS is above 3.5.0 (it is).