Adding label to discover service monitor for prometheus. #97

Hi. I deployed livekit using eks and configured monitoring.
But there was an issue between Prometheus and service monitor. Prometheus can not find the service monitor.
Prometheus check a label which is 'release=prometheus' in the service monitor.
But livekit-server helm chart doesn't make this label.
Please check this helpers code in livekit-helm repository.

I edited service monitor and added the line with release=prometheus and then Prometheus can find the service monitor.

Can I make the PR which add line 'release=prometheus' in service monitor labels if prometheus_port is specified in values.yml?

I used this options.

replicaCount: 2

# Suggested value for gracefully terminate the pod: 5 hours
livekit:
  port: 7880
  log_level: info
  rtc:
    ...
  redis:
    ...
  keys:
    ...
  prometheus_port: 6789
  turn:
    enabled: true
    ...
loadBalancer:
  type: disable

autoscaling:
  ...

resources:
  ...
serviceMonitor:
  create: true
  annotations: {
    "prometheus.io/scrape": "true",
    "prometheus.io/path": "/metrics",
    "prometheus.io/port": "6789"
  }
  name: "prometheus-operator"
  interval: 30s

This is my infrastructure