Describe the bug

The runner crashes on first request (usually program message)

To Reproduce

1. Open VSCode with Safe-DS extension
2. Click on Run button for any Safe-DS source file

Expected behavior

The runner executes the program

Screenshots (optional)

No response

Additional Context (optional)

I would propose to replace the (legacy) flask stack with a quart (successor in a way of flask) stack that does not require monkey patching python internals. This has the added benefit to allow async python functions and in turn being possibly more efficient.

Furthermore, a migration to the socket.io protocol is still possible although not as easy as changing the dependency in flask.