[WIP] Update Docker image to use latest Debian base

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Original prompt

Update the Docker image to use the latest Debian as the base image instead of the current base image.

Requirements:

• Change the base image in the Dockerfile to use the latest Debian (debian:latest or a specific recent Debian version like debian:12)
• Ensure all dependencies and packages are compatible with Debian
• Update any package installation commands to use apt/apt-get as appropriate for Debian
• Maintain all existing functionality of the openssh-server
• Test that the build completes successfully

This pull request was created as a result of the following prompt from Copilot chat.

Update the Docker image to use the latest Debian as the base image instead of the current base image.

Requirements:

• Change the base image in the Dockerfile to use the latest Debian (debian:latest or a specific recent Debian version like debian:12)
• Ensure all dependencies and packages are compatible with Debian
• Update any package installation commands to use apt/apt-get as appropriate for Debian
• Maintain all existing functionality of the openssh-server
• Test that the build completes successfully

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[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/openssh-server/10.0_p1-r9-pkg-dcce22de-dev-3b7c318eb1d66dcdac2054332a9ce0921b3eace3-pr-112/index.html
https://ci-tests.linuxserver.io/lspipepr/openssh-server/10.0_p1-r9-pkg-dcce22de-dev-3b7c318eb1d66dcdac2054332a9ce0921b3eace3-pr-112/shellcheck-result.xml

Tag	Passed
amd64-10.0_p1-r9-pkg-dcce22de-dev-3b7c318eb1d66dcdac2054332a9ce0921b3eace3-pr-112	✅
arm64v8-10.0_p1-r9-pkg-dcce22de-dev-3b7c318eb1d66dcdac2054332a9ce0921b3eace3-pr-112	✅