Fix worker default web_host to be None (faust-streaming#210)

Co-authored-by: Ran Katzir <ran.katzir@valerann.com>
Co-authored-by: Vikram Patki <54442035+patkivikram@users.noreply.github.com>

faust/cli/worker.py

@@ -55,7 +55,7 @@ class worker(AppCommand):
         option(
             "--web-host",
             "-h",
-            default=socket.gethostname(),
+            default=None,
             type=str,
             help=f"Canonical host name for the web server " f"(default: {WEB_BIND})",
         ),
@@ -86,7 +86,7 @@ def _init_worker_options(
         with_web: bool,
         web_port: Optional[int],
         web_bind: Optional[str],
-        web_host: str,
+        web_host: Optional[str],
         web_transport: URL,
         **kwargs: Any,
     ) -> None: