Allow setting the host parameter

In order to run in a Docker container, it is necessary to listen on all interfaces (`0.0.0.0`).
So make it possible to set the host.

Fixes #1

Signed-off-by: Jacob Kiers <code@kiers.eu>

tzk/__main__.py

@@ -83,6 +83,12 @@ class ListenCommand(CliCommand):
 
     @classmethod
     def setup_arguments(cls, parser: argparse.ArgumentParser) -> None:
+        parser.add_argument(
+            "--host",
+            metavar="HOST",
+            help="Host to listen on.",
+            default=str(cm().listen_host or "127.0.0.1"),
+        )
         parser.add_argument(
             "-p", "--port",
             metavar="PORT",
@@ -109,6 +115,7 @@ class ListenCommand(CliCommand):
             tw.exec(
                 [
                     ("listen",
+                    f"host={args.host}",
                     f"port={args.port}",
                     f"username={args.username}",
                     f"password={args.password}")