Fix invalid escape sequence in domain regex

whitelisting_proxy/proxy.py

@@ -275,7 +275,7 @@ def __init__(self, s: str):
  letter_digit = "[a-zA-Z0-9]"
  letter = "[a-zA-Z]"
  label = f"{letter}({letter_digit_hyphen}*{letter_digit}+)*"
- domain = f"({label}\.)*{label}"
+ domain = f"({label}\\.)*{label}"
 
  if not re.match(f"^{domain}$", s):
  raise ValueError("Malformed domain: " + s)