[Feature]: Support .NET 9 for docker

[timbze]

🚀 Feature Request

Currently the docker image is built with .NET 8, when will there be .NET 9 support?

Example

No response

Motivation

Makes it possible to do testing in CI after switching my projects to .NET 9.

[mxschmitt]

Closing as per #3077 (comment).

[timbze]

As per @mxschmitt comment (#3077 (comment)) I realized that I could install dotnet 9 in my own docker image. In case someone wants to use this model: https://github.com/timbze/playwright-docker-plus. I install a few more things in the image for myself so if you like it probably best to create your own image.