Deprecation: NethServer/docs Read the Docs build uses unsupported Ubuntu 20.04

[DavidePrincipi]

Steps to reproduce

• Notice that .readthedocs.yaml in NethServer/docs specifies:

  build:
    os: ubuntu-20.04
  

  See: https://github.com/NethServer/docs/blob/435de2d253f14c746f8579f229eccc5dedfc8e7c/.readthedocs.yaml

• See Read the Docs announcement:

  https://about.readthedocs.com/blog/2026/03/ubuntu-20-04-deprecated/

Expected behavior

• Compatible and secure RTD build

• Use a supported Ubuntu image in .readthedocs.yaml, such as:

  build:
    os: ubuntu-22.04
  

  or

  build:
    os: ubuntu-24.04
  

• Docs builds should not fail after June 1, 2026

Actual behavior

• Builds still use deprecated and soon-to-be-removed Ubuntu 20.04

Components

• NethServer/docs: .readthedocs.yaml
• RTD build infrastructure

See also

• https://about.readthedocs.com/blog/2026/03/ubuntu-20-04-deprecated/
• https://docs.readthedocs.io/en/stable/config-file/v2.html#build-os
• Example affected config: https://github.com/NethServer/docs/blob/435de2d253f14c746f8579f229eccc5dedfc8e7c/.readthedocs.yaml

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Deprecation summary (2026-03-30):

Read the Docs is deprecating build.os: ubuntu-20.04. Projects must upgrade before June 1, 2026, to avoid build failures.