[TypeDeclaration] Handle crash on interface Mixin on ReturnTypeFromStrictConstantReturnRector

[samsonasik]

While there is no longer Mixin interface on latest webmozart/assert, the issue is reproduced at :

• System error: "Scope not available on "PhpParser\Node\Stmt\ClassMethod" node, but is required by a refactorWithScope() method of "Rector\TypeDeclaration\Rector\ClassMethod\ReturnNeverTypeRector" rule. Fix scope refresh on changed nodes first rector#8624

Fixes rectorphp/rector#8624

due to Internal error. on PHPStan enterClass() on MutatingScope

[samsonasik]

All checks have passed 🎉 @TomasVotruba I am merging it ;)