Remove dotnet6 feeds when dependencies publish into dotnet7 feeds.

[ViktorHofer]

from NuGet.config.

Tagging subscribers to this area: @dotnet/runtime-infrastructure
See info in area-owners.md if you want to be subscribed.

Issue Details

---

from NuGet.config.

Author:	ViktorHofer
Assignees:	-
Labels:	blocking-release, area-Infrastructure
Milestone:	7.0.0