Discourse 1.8 is supposed to include newer Unicode stuff, see #releases
Skin tone support for emoji
The current emoji set is the Unicode v3 release. Shrug is v4. I expect v4 will be part of the work done in Discourse 1.8, but I’m just an observer here.
Some previous discussion that might be interesting:
https://meta.discourse.org/t/gay-flag-emoji-not-showing-up/50643/