Describe the feature:

• currently when goss performs a http check like below, "Go-http-client/1.1" will be sent to the server as the user agent

http:
  https://www.google.com:
    status: 200
    allow-insecure: false
    no-follow-redirects: false
    timeout: 1000
    username: ""
    password: ""
    ca-file: ""
    cert-file: ""
    key-file: ""
    proxy: ""
    skip: false
    method: GET

Describe the solution you'd like

• either goss should set its own user agent (like goss/0.4.4) or allow overriding the user agent on a per check basis

Describe alternatives you've considered

• none