fix Prometheus Pushgateway can not enable (#2594)

diff --git a/metrics/options.go b/metrics/options.go
index 8824df6..58542cc 100644
--- a/metrics/options.go
+++ b/metrics/options.go
@@ -76,6 +76,13 @@
 	}
 }
 
+func WithPrometheusPushgatewayEnabled() Option {
+	return func(opts *Options) {
+		enabled := true
+		opts.Metrics.Prometheus.Pushgateway.Enabled = &enabled
+	}
+}
+
 func WithPrometheusGatewayUrl(url string) Option {
 	return func(opts *Options) {
 		opts.Metrics.Prometheus.Pushgateway.BaseUrl = url