Fix ParentOrSiblings

[franciscoaguirre]

We were accepting all type of sibling, not only sibling parachains.

[xlc]

I am not going to block this PR but how do we know if this is doing the right thing? and we definitely need regression test somewhere. I won't require it to happen in this PR / this repo but someone have to make sure it happens.

[muharem]

I am not going to block this PR but how do we know if this is doing the right thing? and we definitely need regression test somewhere. I won't require it to happen in this PR / this repo but someone have to make sure it happens.

we have some tests with xcm-emulator in CI pipeline here paritytech/polkadot-sdk#2566
and we have e2e tests which actually includes asserts for the xcm version updates via subscription (ParentOrSiblings type involved there), we should run them for RC. not yet ideal, but we have some and should continues to add more cases there.

[bkontur]

I would suggest to close this PR, because this will be fixed also here: 44eefcc as a part of 1.6.0 bump