Fix: Make swagger doc compliant to OpenAPI (#3394)

This fixes issues in the swagger.json file. The motivation to do so is to be able to generate API clients using https://openapi-generator.tech Doing so will require further changes to the api spec, but this seems like a good first step since it is now "valid" according to editor.swagger.io and openapi-generator validate.

Fixes #2806

swagger/index.yml

@@ -10,7 +10,7 @@ info:
     name: MIT License
     url: https://opensource.org/licenses/MIT
 host: app.chatwoot.com
-basePath:
+basePath: /
 schemes:
   - https
 produces: