Added new methods

Fixes

• Fixed docs

• Fixed API method names

• Updated MIMEType detection

• Fixed #12

  Now all library errors will be returned to you. A channel for tracking errors in the GreenAPIWebhook structure has also been added.

  Example of error handling when receiving or deleting incoming notifications:

go func() {
    for {
        select {
        case err := <-GreenAPIWebhook.ErrorChannel:
            fmt.Println(err.Error())
        default:
            <-time.After(time.Second)
        }
    }
}()

Enhancements

• Added workflows
• Added dependabot

Features

• Added SendPoll method (thanks to @Jibek100)
• Added GetWaSettings method (thanks to @andreyMalyshkin)
• Added GetAuthorizationCode method (thanks to @Jibek100)

Dependencies

• Added https://github.com/gabriel-vasile/mimetype