Fix gRPC "Waiting for thread pool to idle" in PHPUnit

Originally published at recca0120.github.io When running PHPUnit tests, the message Waiting for thread pool to idle before forking keeps appearing. This is caused by the gRPC extension waiting for the thread pool to become idle before forking. Downgrade the grpc Extension Downgrading grpc to 1.49.0 eliminates this message: pecl install -o -f grpc-1.49.0