build: upgrade to .net 9

Phil91 commented 1 week ago

Description

Upgrade .NET to v9

To have the latest dotnet version in the projects

Refs: #1155

[x] I have followed the contributing guidelines
[x] I have performed IP checks for added or updated 3rd party libraries
[x] I have created and linked IP issues or requested their creation by a committer
[x] I have performed a self-review of my own code
[x] I have successfully tested my changes locally
[x] I have added tests that prove my changes work
[x] I have checked that new and existing tests pass locally with my changes
[x] I have commented my code, particularly in hard-to-understand areas