Use .Net 7 SDK as base image

[joshendriks]

As a followup for both #2411 and #2410

Context:
I am using this image as part of a bitbucket pipeline where Is execute "xUnit driven playwright test" as follows:

image: nwwz/playwright-dotnet:v1.28.0-net7-jammy
       caches:
        - dotnetcore
       script:
        - dotnet dev-certs https --clean
        - dotnet dev-certs https --trust
        - export TESTCONTAINERS_RYUK_DISABLED=true
        - dotnet restore
        - cd tests/End2EndTests
        - dotnet test
       services:
        - docker

I had to replace the official playwright image (mcr.microsoft.com/playwright/dotnet:v1.27.0-focal) with my own (nwwz/playwright-dotnet:v1.28.0-net7-jammy) as part of migrating my app to .NET 7.

nwwz/playwright-dotnet:v1.28.0-net7-jammy was built using the same change as made in this PR.

[mxschmitt]

Playwright uses the current .NET LTS inside the Docker image which is currently .NET 6. (https://dotnet.microsoft.com/en-us/platform/support/policy/dotnet-core)

I recommend to build your own Docker image or use the official one and "inherit" from it via FROM and install your custom .NET version in it.

[joshendriks]

I assume you mean the current latest LTS? At the time of writing .NET Core 3.1 is still a current LTS. As of nov 2023 we will again be in that situation where there are two versions in LTS.

Regardless, I do think it makes sense to also support .NET 7. It is fully supported and production ready. Also, .NET 7 projects do not build on .NET 6. The otherway around does work. So having .NET 7 would give a broader support to the users.

Both of the above reasons might be enough of a justification to support multiple .NET versions. @mxschmitt: Would you like me to create an issue to dicuss it there or would your statement above remain the same?

[mxschmitt]

Yes you are right, I assume the latest LTS.

Definitely it makes sense to have a more rich matrix for different .net versions across the Docker images. Feel free to file a feature request as an issue, then we can do it based on the user requests.