Update dotnet monorepo (major)

This MR contains the following updates:

Package	Type	Update	Change
mcr.microsoft.com/dotnet/aspnet	final	major	8.0-bookworm-slim -> 9.0-bookworm-slim
mcr.microsoft.com/dotnet/aspnet	final	major	6.0-bullseye-slim -> 7.0-bullseye-slim
mcr.microsoft.com/dotnet/sdk	final	major	8.0-bookworm-slim -> 9.0-bookworm-slim
mcr.microsoft.com/dotnet/sdk	final	major	6.0-bullseye-slim -> 7.0-bullseye-slim

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