Failed to update the JSON web key due to missing "alg" field in /oauth/jwks endpoint

Problem/Motivation

I am trying to integrate authentication via ORCID , which provides following endpoints for jwk:
- https://sandbox.orcid.org/oauth/jwks
- https://orcid.org/oauth/jwks
In both endpoints the alg field is missing.
This leads to a situation where the JWK cannot be saved into key value storage, it is skipped in the process due to missing field at line:
https://git.drupalcode.org/project/oidc/-/blob/2.x/src/OpenidConnectReal...

The RFC for JWK states that usage of alg key is optional:
https://datatracker.ietf.org/doc/html/rfc7517#section-4.4

See similar issue for AWS JWT Verify repo: https://github.com/awslabs/aws-jwt-verify/issues/6

Steps to reproduce

Try Integrate ORCID with using oicd module: https://info.orcid.org/documentation/integration-guide/getting-started-w...

Proposed resolution

Do not force check of alg field as it seems to be optional.
The removal of this condition should be safe as the alg field is not used anywhere

docroot/modules/contrib/oidc$ grep -R 'alg' 
docker/keycloak-realm.json:        "algorithm" : [ "HS256" ]
src/OpenidConnectRealm/OpenidConnectRealmBase.php:      if (!isset($key['kid'], $key['kty'], $key['alg'])) {

If I swap following line:

if (!isset($key['kid'], $key['kty'], $key['alg'])) {

with:

if (!isset($key['kid'], $key['kty'])) {

The issue is gone and I can log in without any problems.

Remaining tasks

Add MR with proposed changes

User interface changes

None.

API changes

None.

Data model changes

None.