Incompatibility with promethus/pushgateway:0.10.0

[Gounlaf]

Hi,

Version 0.10.0 of promethus/pushgateway introduced a change in response:

[CHANGE] Check pushed metrics immediately and reject them if inconsistent. Successful pushes now result in code 200 (not 202)

Current version of this client doesn't support it, throwing an exception (see below)

prometheus_client_php/src/Prometheus/PushGateway.php

Line 85 in 215c9ae

if ($statusCode != 202) {