Use template in param phpdoc

It looks like Psalm is able to resolve it thanks to Callback.php, but
PHPStan isn't. To a human reading this phpdoc, it makes more sense to
see the template in both the param and return phpdoc anyway IMO.

src/Framework/Assert.php

@@ -3117,7 +3117,7 @@ public static function isTrue(): IsTrue
     /**
      * @psalm-template CallbackInput of mixed
      *
-     * @psalm-param callable(mixed $callback): bool $callback
+     * @psalm-param callable(CallbackInput $callback): bool $callback
      *
      * @psalm-return Callback<CallbackInput>
      */