Port to new module API

This ports the auth provider to the new module API of Synapse 1.46+.

Docs: https://matrix-org.github.io/synapse/latest/modules/password_auth_provider_callbacks.html

Based on 6c29f4dedd by @anishihara

Fixes https://github.com/ma1uta/matrix-synapse-rest-password-provider/issues/9

README.md

@@ -30,15 +30,19 @@ sudo pip install git+https://github.com/ma1uta/matrix-synapse-rest-password-prov
 If the command fail, double check that the python version still matches. If not, please let us know by opening an issue.
 
 ## Configure
-Add or amend the `password_providers` entry like so:
+Add or amend the `modules` entry like so:
 ```yaml
-password_providers:
+modules:
   - module: "rest_auth_provider.RestAuthProvider"
     config:
       endpoint: "http://change.me.example.com:12345"
 ```
 Set `endpoint` to the value documented with the endpoint provider.
 
+**NOTE:** This requires Synapse 1.46 or later! If you migrate from the legacy `password_providers`, make sure
+to remove the old `RestAuthProvider` entry. If the `password_providers` list is empty, you can also remove it completely or
+comment it out.
+
 ## Use
 1. Install, configure, restart synapse
 2. Try to login with a valid username and password for the endpoint configured