fix PHP example
fix PHP example

kietlieng/zendesk_jwt_sso_examples,zendesk/zendesk_jwt_sso_examples,zendesk/zendesk_jwt_sso_examples,zendesk/zendesk_jwt_sso_examples,zendesk/zendesk_jwt_sso_examples,zendesk/zendesk_jwt_sso_examples,kietlieng/zendesk_jwt_sso_examples,kietlieng/zendesk_jwt_sso_examples,zendesk/zendesk_jwt_sso_examples,kietlieng/zendesk_jwt_sso_examples,zendesk/zendesk_jwt_sso_examples,kietlieng/zendesk_jwt_sso_examples,kietlieng/zendesk_jwt_sso_examples