feat: Add smtp timeout options (#9613)

- Added two Actionmailer's option (open_timeout & read_timeout) to environment variables.

.env.example

@@ -85,6 +85,8 @@ SMTP_OPENSSL_VERIFY_MODE=peer
 # Comment out the following environment variables if required by your SMTP server
 # SMTP_TLS=
 # SMTP_SSL=
+# SMTP_OPEN_TIMEOUT
+# SMTP_READ_TIMEOUT
 
 # Mail Incoming
 # This is the domain set for the reply emails when conversation continuity is enabled