prevent cache locking when read and allow config timeout for cache

[duytiennguyen-okta]

No description provided.

[MikeMondragon-okta]

This PR will be a release, so you'll need to update the CHANGELOG.md file. We don't manage the version in code, it is done with a vMAJOR.MINOR.BUILD formatted tag that triggers goreleaser . I propose the release have the minor version bumped so the version will be 1.4.0. This is because the public method Cache has change on JwtVerifier to Cache func(func(string) (interface{}, error), time.Duration, time.Duration) (utils.Cacher, error) . So the CHANGELOG.md entry should call out the two significant changes - the change to the Cache method, and customizable expiry.

Also, the README.md needs to be updated and improved. In the Customizable Resource Cache section should document how JwtVerifier's default cache is the utils.NewDefaultCache and also the meaning of each of the parameters to the method itself.