use go-jose v4

[mwiesenbauer]

📝 Checklist

• [x] All new/changed/fixed functionality is covered by tests (or N/A)
• [n/a] I have added documentation for all new/changed functionality (or N/A)

🔧 Changes

update go-jose v2 to v4 with new namespace and amended tests and examples accordingly. As a side effect of the update go 1.21 is required.

📚 References

closes https://github.com/auth0/go-jwt-middleware/issues/269

🔬 Testing