go: Exclude CVE-2021-29923 from report list

Upstream don't believe it is a signifiant real world issue and will only
fix in 1.17 onwards. Therefore exclude it from our reports.

https://github.com/golang/go/issues/30999#issuecomment-910470358



Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>