feat(redis): add native JSON session storage for 4.1.0

- Add opt-in SESSION_REDIS_JSON storage for asyncio Redis backends.
- Check JSON command support at startup and reject JSON mode on Trio.
- Read legacy strings and migrate sessions on their next save.
- Validate JSON objects before transactional replacement and expiry.
- Preserve tagged serialization for datetime, tuple, and other types.
- Cover command contracts, error handling, and session round-trips.
- Document server requirements, permissions, and migration limits.
- Normalize indentation and whitespace across code, tests, and examples.
- Bump the package and lockfile to 4.1.0 and update the changelog.
- Refresh the locked pycparser dependency to 3.12.

examples/hello.py

@@ -1,35 +1,30 @@
 # -*- coding: utf-8 -*-
 """
-    Hello
-    ~~~~~
+  Hello
+  ~~~~~
 
-    Quart-Session demo.
+  Quart-Session demo.
 
-    :copyright: (c) 2020 by Kroket Ltd.
-    :license: BSD, see LICENSE for more details.
+  :copyright: (c) 2020 by Kroket Ltd.
+  :license: BSD, see LICENSE for more details.
 """
 from quart import Quart, session
 from quart_session import Session
 
-
 SESSION_TYPE = 'redis'
 
-
 app = Quart(__name__)
 app.config.from_object(__name__)
 Session(app)
 
-
 @app.route('/set/')
 async def set():
-    session['key'] = 'value'
-    return 'ok'
-
+  session['key'] = 'value'
+  return 'ok'
 
 @app.route('/get/')
 async def get():
-    return session.get('key', 'not set')
-
+  return session.get('key', 'not set')
 
 if __name__ == "__main__":
-    app.run(debug=True)
+  app.run(debug=True)