I was a bit confused when I noticed the discord_username parameter in the Discord provider-config.yml file was not actually used when sending the webhook message. It is saved in the Options struct here:

type Options struct {
	ID                      string `yaml:"id,omitempty"`
	DiscordWebHookURL       string `yaml:"discord_webhook_url,omitempty"`
	DiscordWebHookUsername  string `yaml:"discord_username,omitempty"`
	DiscordWebHookAvatarURL string `yaml:"discord_avatar,omitempty"`
	DiscordFormat           string `yaml:"discord_format,omitempty"`
}

But this DiscordWebHookUsername is not actually used further on in the code. This commit simply adds an &username= parameter to the shoutrrr discord URL that is created and makes sure to escape it to allow special characters in the username.

url := fmt.Sprintf("discord://%s@%s?splitlines=no&username=%s", webhookToken, webhookID, 
			url.QueryEscape(pr.DiscordWebHookUsername))
		
sendErr := shoutrrr.Send(url, msg)

Note: This is my first time writing anything in go, but it's a pretty simple change, so it's probably fine

Example