The Ubuntu 20.04 runner image will be fully unsupported by April

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Describe the bug

GitHub is removing support for 20.04 runners soon. We need to remove our usage ASAP.

Affected OS

• Windows
• Linux
• macOS
• Other (specify below)

Additional OS information

No response

MsQuic version

main

Steps taken to reproduce bug

n/a

Expected behavior

n/a

Actual outcome

n/a

Additional details

No response