Remove fmt.Print and etc.

[Dzyanis Kuzmenka]

fmt.Print, fmt.Printf, fmt.Println and etc. can clog output. For example: a report of go test. Also, we can't test it.

If we use it for logging then lets just use logger instead.
If we really want to throw some message to the stdout then we can use io.Writer

func message(w io.Writer) error {
    _, err := w.Write([]byte("message"))
    return err
}

or just return the message

func message() (string, error)  {
    return "message", nil
}

and handle somewhere in the main func.

The linter forbidigo can catch such cases. I'd recommend to enable it.

provider/nowsms/nowsms.go:67:2: use of `fmt.Println` forbidden by pattern `^(fmt\.Print(|f|ln)|print|println)$` (forbidigo)
        fmt.Println("Message sent: ", message.Text)
        ^
provider/tencentcloud/tencentcloud.go:79:4: use of `fmt.Printf` forbidden by pattern `^(fmt\.Print(|f|ln)|print|println)$` (forbidigo)
                        fmt.Printf("An API error has returned: %s", err)
                        ^
provider/tencentcloud/tencentcloud.go:87:3: use of `fmt.Printf` forbidden by pattern `^(fmt\.Print(|f|ln)|print|println)$` (forbidigo)
                fmt.Printf("%s", b)
                ^
provider/kavenegar/kavenegar.go:64:2: use of `fmt.Println` forbidden by pattern `^(fmt\.Print(|f|ln)|print|println)$` (forbidigo)
        fmt.Println("Message sent: ", message.Text)
        ^
provider/ghasedak/ghasedak.go:63:2: use of `fmt.Println` forbidden by pattern `^(fmt\.Print(|f|ln)|print|println)$` (forbidigo)
        fmt.Println("Message sent: ", message.Text)