internals: add automatic generation

Closes #754
Closes #755

Author: tulir

client.go

@@ -37,7 +37,7 @@ import (
 )
 
 // EventHandler is a function that can handle events from WhatsApp.
-type EventHandler func(evt interface{})
+type EventHandler func(evt any)
 type nodeHandler func(node *waBinary.Node)
 
 var nextHandlerID uint32
@@ -778,7 +778,7 @@ func (cli *Client) sendNode(node waBinary.Node) error {
 	return err
 }
 
-func (cli *Client) dispatchEvent(evt interface{}) {
+func (cli *Client) dispatchEvent(evt any) {
 	cli.eventHandlersLock.RLock()
 	defer func() {
 		cli.eventHandlersLock.RUnlock()

group.go

@@ -863,7 +863,7 @@ Outer:
 	cli.groupParticipantsCache[evt.JID] = cached
 }
 
-func (cli *Client) parseGroupNotification(node *waBinary.Node) (interface{}, error) {
+func (cli *Client) parseGroupNotification(node *waBinary.Node) (any, error) {
 	children := node.GetChildren()
 	if len(children) == 1 && children[0].Tag == "create" {
 		return cli.parseGroupCreate(&children[0])