GitHub Actions is easier to use and maintain. For example, GitHub Actions is more popular and widely used, and so more familiar. It's easier to maintain a single system. Also core devs can restart failed GitHub Actions whereas they can't for Azure Pipelines. Both are owned by Microsoft and I believe they run on much the same infra.

There's a lot of duplication of tests between Azure Pipelines and GitHub Actions.

Let's remove the duplicated tests, and move the unique things over to GitHub Actions. For example, patchcheck is only run on AP.

We might not necessarily need to port things directly over, it may be possible to replicate equivalent checks in another way, possible with a pre-commit or Ruff lint rule. Let's evaluate these separately.

Related issues/PRs:

• Azure Pipelines: macOS CI Tests and Ubuntu CI Tests (coverage) jobs are always skipped #109395
  • gh-109395: Remove skipped macOS builds from Azure Pipelines #109400
  • gh-109395: Remove skipped coverage job from Azure Pipelines #109412
• CI: Remove docs build from Azure Pipelines #105823
• Make Azure Pipelines optional on GitHub PRs #84018
  • bpo-39837: Disable macOS tests on Azure Pipelines #18818

Linked PRs

• gh-109408: Remove Ubuntu unit tests from Azure Pipelines #109452
• gh-109408: Azure Pipelines: test 3.12 branch #109453
• gh-109408: Run patchcheck in GitHub Actions #109459
• [3.12] gh-109408: Remove Ubuntu unit tests from Azure Pipelines (GH-109452) #109519
• [3.11] gh-109408: Remove Ubuntu unit tests from Azure Pipelines (GH-109452) #109520
• [3.12] gh-109408: Azure Pipelines: test 3.12 branch (GH-109453) #109535
• [3.11] gh-109408: Azure Pipelines: test 3.12 branch (GH-109453) #109536
• gh-109408: Move Windows builds from Azure Pipelines PR to GitHub Actions #109569
• [3.12] gh-109408: Move Windows builds from Azure Pipelines PR to GitHub Actions (GH-109569) #109623
• [3.11] gh-109408: Move Windows builds from Azure Pipelines PR to GitHub Actions (GH-109569) #109624
• gh-109408: Add the docs whitespace check from patchcheck to pre-commit #109854
• GH-109408: Move the C file whitespace check from patchcheck to pre-commit #109890
• GH-109408: Move the Python file whitespace check from patchcheck to pre-commit #109891
• gh-109408: Stop running patchcheck in CI #109895
• [3.12] gh-109408: Add the docs whitespace check from patchcheck to pre-commit (GH-109854) #110594
• [3.11] gh-109408: Add the docs whitespace check from patchcheck to pre-commit (GH-109854) #110595
• [3.12] GH-109408: Move the Python file whitespace check from patchcheck to pre-commit (GH-109891) #110633
• [3.12] GH-109408: Move the C file whitespace check from patchcheck to pre-commit (GH-109890) #110636
• [3.11] GH-109408: Move the C file whitespace check from patchcheck to pre-commit (GH-109890) #110640
• [3.11] GH-109408: Move the Python file whitespace check from patchcheck to pre-commit (GH-109891) #110641
• gh-109408: Revert pre-commit whitespace checks pending portable solution #110726
• [3.12] gh-109408: Revert pre-commit whitespace checks pending portable solution (GH-110726) #110730
• GH-109408: Add a make lint target #122333
• GH-109408: Remove .azure-pipelines/pr.yml #122643