Upgrade go-msgpack to v2 2.1.1

[swenson]

This is mostly a no-op for Consul as Consul mostly uses consul-net-rpc and the default time.Time encoding for go-msgpack 2.1.1 is set to the go-msgpack-0.5.5-compatible encoding by default, so no changes should be necessary in code.

go-msgpack 2.1.1 was specifically designed to honor backwards compatibility with 1.1.5 and 0.5.5, and to clean up the code base to be more maintainable. See the release notes for go-msgkack 2.1.0 for more details.

I tested this by running this code, and booting up a cluster with a node also running the prior version of Consul (before the upgrade). The node came up smoothly, even after changing leadership between them.

This relies on

• [x] https://github.com/hashicorp/serf/pull/705
• [x] https://github.com/hashicorp/raft-boltdb/pull/38
• [x] https://github.com/hashicorp/raft/pull/577
• [x] https://github.com/hashicorp/memberlist/pull/292

and will need to be updated after they are merged to get the go.mod fixes removed.

PR Checklist

• [ ] updated test coverage
• [x] external facing docs updated
• [x] appropriate backport labels added
• [x] not a security concern

[github-actions[bot]]

This pull request has been automatically flagged for inactivity because it has not been acted upon in the last 60 days. It will be closed if no new activity occurs in the next 30 days. Please feel free to re-open to resurrect the change if you feel this has happened by mistake. Thank you for your contributions.

[swenson]

This is still relevant, and I'm happy to do any follow-up required.

[github-actions[bot]]

This pull request has been automatically flagged for inactivity because it has not been acted upon in the last 60 days. It will be closed if no new activity occurs in the next 30 days. Please feel free to re-open to resurrect the change if you feel this has happened by mistake. Thank you for your contributions.

[github-actions[bot]]

Closing due to inactivity. If you feel this was a mistake or you wish to re-open at any time in the future, please leave a comment and it will be re-surfaced for the maintainers to review.