Add Debian Bookworm images for .NET 6/7

[richlander]

.NET 6 images are based on Debian Bullseye. Bullseye will go out of support ahead of .NET 6. We should start producing Debian Bookworm images for .NET 6. Also, OpenSSL 1.x EOL is before .NET 6 EOL. Debian Bullseye includes OpenSSL 1.x and Bookworm 3.x.

• OpenSSL 1.1.1 EOL: September 11, 2023
• Debian Bullseye EOL: ~ July, 2024
• .NET 6 EOL: November 12, 2024

The expectation is the following:

• 6.0-bullseye-slim tags will be updated through .NET 6 EOL, based on Debian Bullseye.
• 6.0 tags will continue to be based on bullseye-slim images for compatibility reasons, even though they may have more CVEs.
• 6.0-bookworm-slim tags will be based on Debian Bookworm and be opt-in (AKA, you need to update your FROM statement).
• We will start by publishing 6.0-bookwork-slim tags in dotnet/nightly repos and then publish to dotnet (main) repos after Bookworm is GA.

6.0 images:

dotnet-docker/src/runtime-deps/6.0/bullseye-slim/arm64v8/Dockerfile

Line 1 in f4786b8

FROM arm64v8/debian:bullseye-slim

.NET 8 images are already based on Bookworm:

dotnet-docker/src/runtime-deps/8.0/bookworm-slim/arm64v8/Dockerfile

Line 1 in f4786b8

FROM arm64v8/debian:bookworm-slim

.NET 7 images don't need to be changed since .NET 7 EOL is ahead of Bullseye or OpenSSL 1.x EOL.

More info:

• https://wiki.debian.org/DebianReleases
• https://github.com/dotnet/core/blob/main/releases.md
• https://www.openssl.org/blog/blog/2023/03/28/1.1.1-EOL/

[mthalman]

[Triage]
This will help to fill in the gap of having a supported Debian version for .NET 6 between July and November (2024).

[mthalman]

@lbussell - You can grab my branch at https://github.com/dotnet/dotnet-docker/tree/dev/mthalman/issue4535-bookworm which already starts this work. I think all that's left is to update the image size baselines.