fix(test_email): `which net-tools` is always false, use `which netstat` instead

tests/test_email.py

@@ -16,7 +16,7 @@ try:
 except ImportError:
     subprocess.check_call(['apt-get', '-qq', '-y', 'install', 'python3-spf'])
     import spf
-if subprocess.call(['which', 'net-tools']) != 0:
+if subprocess.call(['which', 'netstat']) != 0:
     subprocess.check_call(['apt-get', '-qq', '-y', 'install', 'net-tools'])
 
 YELLOW = '\033[93m'