Fixed Athenz repository name

[merlimat]

Motivation

The Athenz repository has been moved from github.com/yahoo/athenz to github.com/AthenZ/athenz.

The command to fetch Pulsar client is failing because of that:

$ go get -u "github.com/apache/pulsar-client-go/pulsar"
go get: github.com/yahoo/[email protected] updating to
	github.com/yahoo/[email protected]: parsing go.mod:
	module declares its path as: github.com/AthenZ/athenz
	        but was required as: github.com/yahoo/athenz

[cckellogg]

I think the test file needs updating too
https://github.com/apache/pulsar-client-go/blob/master/pulsar/internal/auth/athenz_test.go

[alvaradojl]

I just tried go get -u "github.com/apache/pulsar-client-go/pulsar" and I got the same error. Is there some kind of regression?