Fix an encoding issue in sendcontrol

[ddddhm1234]

fix the bug in sendcontrol function.
let us take an example of sending ctrl+c through this function,

• the oiriginal code

byte = str(bytes([0x03]))

the byte would be r"b\x03"

• the modified code

byte = bytes([0x03]).decode("ascii")

the byte would be "\x03"

[andfoy]

Thanks for this contribution @ddddhm1234!