feat: update Let's Encrypt to official endpoint

Author: zhengkunwang223

agent/utils/ssl/acme.go

@@ -182,7 +182,6 @@ func getCaDirURL(accountType, customCaURL string) string {
 	switch accountType {
 	case "letsencrypt":
 		caDirURL = "https://acme-v02.api.letsencrypt.org/directory"
-		caDirURL = "https://acme-staging-v02.api.letsencrypt.org/directory"
 	case "zerossl":
 		caDirURL = "https://acme.zerossl.com/v2/DV90"
 	case "buypass":