set sender_localpart in registration.yml.j2 template to variable

roles/custom/matrix-bridge-hookshot/templates/registration.yml.j2

@@ -25,7 +25,7 @@ namespaces:
     - regex: "#github_.+:{{ matrix_domain }}"
       exclusive: true
 
-sender_localpart: hookshot
+sender_localpart: {{ matrix_hookshot_bot_localpart }}
 url: "http://{{ matrix_hookshot_container_url }}:{{ matrix_hookshot_appservice_port }}" # This should match the bridge.port in your config file
 rate_limited: false