Use to_json in appservice-slack config.yaml.j2

roles/custom/matrix-bridge-appservice-slack/templates/config.yaml.j2

@@ -27,11 +27,11 @@ rtm:
 {% if matrix_appservice_slack_puppeting_enabled %}
 puppeting:
   enabled: true
-  onboard_users: {{ matrix_appservice_slack_puppeting_onboard_users|lower }}
+  onboard_users: {{ matrix_appservice_slack_puppeting_onboard_users | to_json }}
 
 oauth2:
-  client_id: "{{ matrix_appservice_slack_puppeting_slackapp_client_id }}"
-  client_secret: "{{ matrix_appservice_slack_puppeting_slackapp_client_secret }}"
+  client_id: {{ matrix_appservice_slack_puppeting_slackapp_client_id | to_json }}
+  client_secret: {{ matrix_appservice_slack_puppeting_slackapp_client_secret | to_json }}
 {% endif %}
 
 {% if matrix_appservice_slack_team_sync_enabled %}
@@ -39,7 +39,7 @@ team_sync:
   all:
     channels:
       enabled: true
-      alias_prefix: "{{ matrix_appservice_slack_team_sync_alias_prefix }}"
+      alias_prefix: {{ matrix_appservice_slack_team_sync_alias_prefix | to_json }}
     users:
       enabled: true
 {% endif %}