imapclient: use dialer in DialInsecure

The default `net` package dialer doesn't have timeout. The dialer defined and used in client connection does.

Author: snekROmonoro

imapclient/client.go

@@ -212,7 +212,7 @@ func NewStartTLS(conn net.Conn, options *Options) (*Client, error) {
 
 // DialInsecure connects to an IMAP server without any encryption at all.
 func DialInsecure(address string, options *Options) (*Client, error) {
-conn, err := net.Dial("tcp", address)
+conn, err := dialer.Dial("tcp", address)
 if err != nil {
 return nil, err
 }