[FEATURE] - NTFY authentication to improve security

[lfelipe1501]

@Krillsson You could add an authentication section for using ntfy, this is to improve security, because if I use and ntfy URL that is publicly exposed I don't know how to protect the topic.

notifications:
  serverName: lfsystems-ntfy
  ntfy:
    enabled: true
    url: "https://ntfy.lfsystems.com.co"
    topic: kSZhmW4XXwF6spV2
    # Optional user and password
    user: krillsson
    pass: y0urStrongP4ss
# advertise service in local network for easier client setup
mDNS:
  enabled: true

This would be greatly appreciated.