build(deps): bump github.com/envoyproxy/go-control-plane/envoy from 1.37.1-0.20260304210048-a81710db7097 to 1.39.0 in /examples/grpc-ext-proc

build(deps): bump github.com/envoyproxy/go-control-plane/envoy from 1.37.1-0.20260304210048-a81710db7097 to 1.39.0 in /examples/grpc-ext-proc #34622