errors: implement ErrIs

errors.go

@@ -1,6 +1,7 @@
 package telebot
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 )
@@ -254,6 +255,11 @@ func Err(s string) error {
 	}
 }
 
+// ErrIs checks if the error with given description matches an error err.
+func ErrIs(s string, err error) bool {
+	return errors.Is(err, Err(s))
+}
+
 // wrapError returns new wrapped telebot-related error.
 func wrapError(err error) error {
 	return fmt.Errorf("telebot: %w", err)