"-no-ansi" option is not respected if unknown engine passed

[librolibro]

If unknown engine choosen, ANSI codes for text color/style reset will be applied - even if -no-ansi option passed to trans. It also doesn't matter whether stderr a tty or not.

Output of trans --version:

Translate Shell       0.9.7.1-git:faff2c9

platform              Linux
terminal type         alacritty
bi-di emulator        [N/A]
gawk (GNU Awk)        5.3.1
fribidi (GNU FriBidi) 1.0.16
audio player          mpv --no-config
terminal pager        less
web browser           brave
user locale           en_US.UTF-8 (English)
host language         en
source language       auto
target language       en
translation engine    auto
proxy                 [NONE]
user-agent            Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36 Edg/104.0.1293.54
ip version            [DEFAULT]
theme                 default
init file             [NONE]

Report bugs to:       https://github.com/soimort/translate-shell/issues