False positive with template covariant

# Bug report

I'm not 100% sure but I don't think there is much of a difference between toArray and ToPairs regarding type variance, right?

Or In case the error is correct then how should I fix it? :thinking: 

### Code snippet that reproduces the problem

https://phpstan.org/r/ccc12749-6dfd-4e0d-abf5-54dcd11e6fd6

### Expected output

no error
