Fix private In6AddrGenMode

[Toorero]

This is related to #149. I forgot to include In6AddrGenMode in the pub use of the mod.rs of the link module.

[Toorero]

I'm not sure how relaxed you are in terms of commit history rewrites. If you are you could just squash commits 5f441ac and 7daf895.

Just do:

git checkout main
git pull
git rebase -i 7daf895~1                # change pick of 7daf895 to edit
git cherry-pick --no-commit fix/addr_gen_mode_enum
git commit --amend --no-edit
git push --force                       # could lead to commit loss if commits arive at Github after initial pull