Multiplication mutator should not mutate when return value is integer

[maks-rafalko]

Question	Answer
Infection version	0.22.0
Test Framework version	PHPUnit
Reproducer	https://infection-php.dev/r/dld0

The following mutation does not make sense:

public function mul(int $a, int $b): int
{
-    return $a * $b;
+    return $a / $b;
}

because it is always killed since result type of new $a / $b expression is float but int is expected.

Such mutant is killed with the following error message:

TypeError: Return value of Infected\SourceClass::mul() must be of the type int, float returned