gaby: do not include the issue itself in the related issue list

[hyangah]

From golang/go#67901 (comment)

golang/go issue 70569#issuecomment-2499863712 references itself.

(https://github.com/golang/go/issues/70569) <!-- score=0.99978 -->

The similarity score is not 1.0 (precision error?).
Adjust the filtering to check the issue number.