Bugfix/Escape CSI sequences correctly

[lightr4in]

I could not use the library on my Linux machine until I escaped the CSI sequences correctly: \e -> \\e

This PR should fix it for any unixoid system.

[morrisfranken]

Hi lightr4in, thanks for reporting this. However, this does not seem to work on any of the machines I've tested it on (Ubuntu 20.04/22.04, gnome terminal), and instead of making the text bold, it adds additional escape characters to the prompt. E.g.:

argparse_test source_path destination -k=5 --alpha=1 --beta 3.3 --gamma --numbers=1,2,3,4,5 --numbers2 6,7,8 --files f1 f2 f3 --custom hello_custom --optional 1 --verbose
    arg_0(Source ...) : \e[1msource_path\e[0m
    arg_1(Destina...) : \e[1mdestination\e[0m
        arg_2(Others) : unknown
                   -k : \e[1m5\e[0m
           -a,--alpha : \e[1m1\e[0m
            -b,--beta : \e[1m3.3\e[0m
              --beta2 : 0.6f
           -g,--gamma : \e[1m0.5\e[0m
          -c,--custom : \e[1mhello_custom\e[0m
         -n,--numbers : \e[1m1,2,3,4,5\e[0m
           --numbers2 : \e[1m6,7,8\e[0m
              --files : \e[1mf1,f2,f3\e[0m
        -o,--optional : \e[1m1\e[0m
            -f,--flag : false
         -v,--verbose : \e[1mtrue\e[0m
               --help : false

Can you explain a bit more about what OS are you using, and what terminal?