Fix mbc init python template

maubot/cli/res/plugin.py.j2

@@ -1,6 +1,9 @@
-from maubot import Plugin
+from typing import Type
 {% if config %}
 from mautrix.util.config import BaseProxyConfig, ConfigUpdateHelper
+{% endif %}
+from maubot import Plugin
+{% if config %}
 
 class Config(BaseProxyConfig):
     def do_update(self, helper: ConfigUpdateHelper) -> None:
@@ -9,18 +12,14 @@ class Config(BaseProxyConfig):
         helper.copy("example_2.value")
 {% endif %}
 
-class {{ name }}:
-    async def start() -> None:
-{% if config %}
+class {{ name }}(Plugin):
+    async def start(self) -> None:{% if config %}
         self.config.load_and_update()
-        self.log.debug("Loaded %s from config example 2", self.config["example_2.value"])
-{% else %}
-        pass
-{% endif %}
+        self.log.debug("Loaded %s from config example 2", self.config["example_2.value"]){% else %}
+        pass{% endif %}
 
-    async def stop() -> None:
+    async def stop(self) -> None:
         pass
-
 {% if config %}
     @classmethod
     def get_config_class(cls) -> Type[BaseProxyConfig]: