* fixing php8.2 test deprecations
fixes various dynamic property deprecations in the tests themselves
* fixing phpunit9 deprecation
at() matcher is deprecated, to be removed in phpunit 10. switch to withConsecutive
* adding channel property to Grpc\Call
this resolves "Creation of dynamic property Grpc\Call::$channel is deprecated" in php 8.2
* skip implicit cast test in 8.1+
implicit casting from float to int is deprecated from 8.1, so users would receive a deprecation warning if trying to do this
* php8.2rc4
Stanley Cheung