This updates the Code of Conduct to the Contributor Covenant v2.1 version (we were using the 2.0 version until now). Changes are very minor. As far as I can tell, the only content difference is the explicit mention of _caste_ and _color_ among the potential traits that could cause harassment.
Then it just changes the format a bit to make links a bit more user friendly, by not posting URLs directly.
But I have a question: should we update the contact method? It currently says the following:
> Instances of abusive, harassing, or otherwise unacceptable behavior may be reported to the community leaders responsible for enforcement at [discord](https://discord.gg/tUFFk9Y) by contacting _JaseW_.
Maybe we should mention the `@boa-dev` group, and that they can contact anyone there. What do you think? I would also like to update this before https://github.com/boa-dev/ryu-js/pull/22