Remove skip-duplicate option from NuGet push command

[zvirja]

Follow up on #987. Remove skip-duplicate options, as I realized it would be nicer to fail and make it explicit. A new thought next morning :)

[dtchepak]

Thanks a lot @zvirja . 🫶

Happy to go with trigger-on-tag, although would like to have a guard rail that prevents that if CHANGELOG isn't updated (e.g. still has unreleased heading, or latest version doesn't match tag), but can look at that in a separate commit (or just drop changelog in favour of github releases changelogs?)

[zvirja]

@dtchepak Shall we proceed with GitHub change log and drop our own one? I feel that:

• Simpler and we will have less burden maintaining it
• GitHub generates it pretty good
• Higher changes of being consistent as we could easily overlook updating change log (I do that all the time)
• I don't think a lot of people are reading it. Rather they just use new lib and throw bugs
• In days of AI it will most likely be read by AI anyway. And it can read GitHub one.

This way we'll be also more aligned with other repos, as most of them use GH these days. And less hassle for us 😊

[dtchepak]

@zvirja yeah happy to drop changelog in that case. I can manually edit release notes to include thanks for people that have helped out (often that doesn't come across from just the commits).

I was about to prep 6.2 release with the generic matches fix but maybe we can do this via the new process instead (very excited! 😂 ).

I've updated the release procedure but please fix up any details I've stuffed up if you get a chance 🙏