Remove Ubuntu 20.04 container image from CI pipeline — EOL

[richlander]

An org-wide audit of the dotnet org against the .NET supported OS matrix found references to Ubuntu 20.04, which reached end-of-life in April 2025.

Part of .NET OS Support Tracking. See also: dotnet/runtime#125690, dotnet/dotnet-buildtools-prereqs-docker#1605.

Tracking

• UbuntuContainer — prereqs:ubuntu-20.04-20240708213715-dcf0bb9 → prereqs:ubuntu-26.04
• MS packages apt source — update from ubuntu/20.04 to ubuntu/26.04
• kitware apt source — update from focal to current Ubuntu codename

Details

TorchSharp/azure-pipelines.yml

Line 49 in 5782540

image: mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-20.04-20240708213715-dcf0bb9

TorchSharp/azure-pipelines.yml

Line 36 in 5782540

wget https://packages.microsoft.com/config/ubuntu/20.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb

TorchSharp/azure-pipelines.yml

Line 32 in 5782540

echo 'deb [signed-by=/usr/share/keyrings/kitware-archive-keyring.gpg] https://apt.kitware.com/ubuntu/ focal main' | sudo tee /etc/apt/sources.list.d/kitware.list

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This issue was generated by GitHub Copilot CLI v1.0.7 via the update-supported-os skill.