Removed dotnet6, dotnet-tools, and dotnet-tools-transport nuget feeds.

[AraHaan]

Checklist

• [x] I have read the Code of Conduct and the Contributing files before opening this issue.
• [x] I have verified the issue this pull request fixes or feature this pull request implements is to the current release.
• [x] I am using the latest stable release with the above code fix or the current main branch if code changes are present (prerelease code changes).
• [x] I have debugged and tested my changes before submitting this issue and that everything should just work.

Describe the issue this fixes / feature this adds

[mergify[bot]]

This pull request is about to be automerged.