Make password a template

Author: ccrisan

README.md

@@ -83,7 +83,9 @@ available context is limited however to `device_attrs`.
 
 ### `password`
 
-Indicates a password to supply for authentication. 
+Indicates a password to supply for authentication. The value is in fact a template that can be customized following the
+rules  described in [Template Notifications](https://github.com/qtoggle/qtoggleserver/wiki/Template-Notifications). The
+available context is limited however to `device_attrs`.
 
  * type: `string`
  * default: `null`

qtoggleserver/mqtt/mqtteventhandler.py

@@ -84,6 +84,8 @@ def __init__(
         self._client_id_template: Template = self.make_template(self.client_id)
         if self.username:
             self._username_template = self.make_template(self.username)
+        if self.password:
+            self._password_template = self.make_template(self.password)
 
         self.client_logger: logging.Logger = self.logger.getChild('client')
         if not self.client_logging:
@@ -109,12 +111,15 @@ async def _client_loop(self) -> None:
                 username = None
                 if self._username_template:
                     username = await self._username_template.render_async(template_context)
+                password = None
+                if self._password_template:
+                    password = await self._password_template.render_async(template_context)
                 async with aiomqtt.Client(
                     hostname=self.server,
                     port=self.port,
                     tls_context=tls_context,
                     username=username,
-                    password=self.password,
+                    password=password,
                     client_id=client_id,
                     logger=self.client_logger,
                 ) as client: