[BUG] input iterm2 multi panes would got unexpected result

[yeqown]

reproduction:

1. open multi panes in iterm2 with differenct project
2. press Command + Shitf + I to input into panes at the same time
3. using gitlab-flow any command to execute

It did not work as expected but raiseda fatal message:

[INF] "2025-03-05T13:56:30+08:00" msg="gitlab-flow oauth authorization succeeded!"
panic: send on closed channel

goroutine 46 [running]:
github.com/yeqown/gitlab-flow/internal/gitlab-operator.(*gitlabOAuth2Support).requestToken.func1()
	/Users/apple/projects/opensource/gitlab-flow/internal/gitlab-operator/gitlab_oauth2.go:365 +0x2c
created by github.com/yeqown/gitlab-flow/internal/gitlab-operator.(*gitlabOAuth2Support).requestToken
	/Users/apple/projects/opensource/gitlab-flow/internal/gitlab-operator/gitlab_oauth2.go:362 +0x8c4