- Remove CHANGELOG.md

We haven't been good about keeping it up-to-date.
Consult git history or Github Releases for change information

Fixes #196

- Remove broken shields.io tests status.

The test status shield isn't working.
Consult the Github Actions output to see current test status.

- Clarify different go-jose versions

More aggressively recommend users migrate to Version 4, and include
notes about encoding/json/v2 for the Version 5 of go-jose. Document that
we will support the two current Golang releases on V4.

Fixes #184

- Fixup markdown table borders

This PR removes the dependency on testify. Unit tests of the new code
are included.

**Why remove testify:**

- testify is a dependency (and has indirect dependencies)
- testify uses go-spew which is not maintained anymore (see
stretchr/testify#1638)
- go-spew is in a 'not allowed' list in Kubernetes (see
kubernetes/kubernetes#103942) and therefore
kubernetes can't use go-jose v4 (see
kubernetes/kubernetes#123252)
- Equal was used to compare complex structs, but Equal in testify
doesn't fully compare values, see
stretchr/testify#1616
- removing testify would remove the dependencies on external projects,
reducing operational risk, as go-jose has a lot of users

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Matthew McPherrin <mattm@letsencrypt.org>
Co-authored-by: Jacob Hoffman-Andrews <github@hoffman-andrews.com>

The switch statement is exited subsequent to the first condition that
evaluates to true, yet it is evident from the context that the intention
was to cover all possibilities.

Found by PostgresPro

Related: 98e5a54 ("Print all missing fields at once")

Ultimately we want to ignore unsupported key types in JSONWebKeySets
(#26 / #130), but we are blocked on doing a breaking change release.
In the meantime, we can have JSONWebKey (the singular version)
return ErrUnsupportedKeyType.

This allows users to write their own JWKS umarshalling method to
ignore unsupported key types, eg.
https://github.com/zitadel/oidc/blob/045b59e5a55be97ba180fdaae96fb66302a03353/pkg/client/rp/jwks.go#L221-L235.

JSONWebKey is marked as a valid type in Recipient but was rejected further down the line when calling `makeJWERecipient()`.

These functions were used few places, and could generally be replaced
with a simple `if` and a more informative error message, or a more
specific assert function.

Follow up to #197