ImplementedReturnTypeMismatch on method implemented in non-template trait and declared abstract in a templated trait

[ptomulik]

https://psalm.dev/r/97a5b80220

It's not a duplicate of #6937. The #6963 does not fix this, but I think I have a fix for it.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/97a5b80220

<?php
trait ImplementorTrait {
    /** @var int */
    private $value;

    public function getValue(): int {
        return $this->value;
    }
}

/** @psalm-template T */
trait GuideTrait {
    /** @psalm-return T */
    abstract public function getValue();
}

class Test {
    use ImplementorTrait;

    /** @template-use GuideTrait<int> */
    use GuideTrait;

    public function __construct() {
        $this->value = 123;
    }
}

Psalm output (using commit eca56c0):

ERROR: ImplementedReturnTypeMismatch - 6:33 - The inherited return type 'T:GuideTrait as mixed' for GuideTrait::getValue is different to the implemented return type for ImplementorTrait::getvalue 'int'