Update Contributor Covenant Code of Conduct to 2.1

[michalrus]

I found we were missing “sexual characteristics” in v1.4 vs. the original on their website, so we investigated some more with @abailly-iohk, and there seems to be a new version 2.1.

It does seem like they are changing those CoCs after releases, e.g. this is the commit that ±answers my initial question → https://github.com/EthicalSource/contributor_covenant/commit/375118ca945fe53f64722299795afcd313a57e8e.

Those 2 versions on the newest release tag are:

• v1.4: https://github.com/EthicalSource/contributor_covenant/blob/2.1/content/version/1/4/code-of-conduct.md
• v2.1: https://github.com/EthicalSource/contributor_covenant/blob/2.1/content/version/2/1/code_of_conduct.md

The main difference seems to be in adding “Enforcement Guidelines”, as seen in this PR’s diff.

[michaelpj]

LGTM, thanks for updating this!