Deadlock calling `Event` in after-event callback when current state == dst

[naumov-andrey]

Hi,
I have a deadlock when trying to initiate transition in after-event callback for dst == src

Simpliest example

package main

import (
	"context"
	"fmt"

	"github.com/looplab/fsm"
)

func main() {
	fsm := fsm.NewFSM(
		"start",
		fsm.Events{
			{Name: "created", Src: []string{"start"}, Dst: "start"},
			{Name: "checked", Src: []string{"start"}, Dst: "checked"},
		},
		fsm.Callbacks{
			"after_created": func(ctx context.Context, e *fsm.Event) {
				// some checks
				if err := e.FSM.Event(ctx, "checked"); err != nil {
					fmt.Println(err)
				}
			},
		},
	)

	if err := fsm.Event(context.Background(), "created"); err != nil {
		panic(fmt.Sprintf("Error encountered when triggering the run event: %v", err))
	}
}

It seems to be a bag that there is no eventMu.Unlock() for an event without state transition
fsm.go#L335