feat: Support JWKS for JWT validation

[broncha]

Hi all,

I am working on adding support for JWKS in Mercure. With this update, you would simply configure the JWKS URL and Mercure would validate the subscriber and publisher JWT based on the Key ID and the keys in the JWKS.

I have everything working (tested the binary with other apps publishing and subscribing). However, I am struggling with timeout on one of the tests. Can anyone have a look at it and point out my mistake with the test?

Here is the commit that adds JWKS support to Mercure broncha@f6d9015

And the test that is timing out is TestSubscribePrivateWithJWKS in subscribe_test.go

[dunglas]

Hi @broncha. Nice feature! Don't hesitate to open a PR, I'll try helping to have the tests green.

[broncha]

@dunglas Opened a draft PR here #813