Handle non- utf-8 characters

[adamtheturtle]

subprocess-tee errors when the subprocess prints a non- utf-8 character.
This is a difference between subprocess and subprocess-tee.

Reproduction

# my_script.sh
echo -e "\xC0\x80"

# reproducer.py
import subprocess
import subprocess_tee

print("Subprocess:")

subprocess.run(args=["bash", "my_script.sh"])

print("Subprocess tee:")

subprocess_tee.run(args=["bash", "my_script.sh"])

subprocess will replace invalid bytes with a placeholder character, while subprocess-tee errors with:

UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc0 in position 0: invalid start byte

Fix

I suggest using errors="replace" on line.decode().