What it does

Three tables from three sources with one snapshot date, copied rather than fetched: a check that needs the network fails in an air-gapped build, and a table that refreshes itself cannot be reviewed in a pull request.
ubuntu-22.04 is a prefix of ubuntu-22.04-arm64 and @v3 of @v3.1.0, so matches are bounded and longest-first; a SHA pin is not guessed at; a matrix list yields every version in it while ${{ matrix.python-version }} yields none.
Being four majors behind is printed separately from having a published end date. The first is worth knowing; only the second should fail a build.
Dependabot raises a pull request when a version moves. It does not tell you the thing you have stops working on a named day.
--check-source asks the feeds whether these dates are still the published ones. endoflife.date serves JSON, so a moved date is reported with both values rather than guessed at from prose.
Eleven of the tests are cases of naming a thing rather than using it: an image inside echo, the half of a line after a hash, python-version inside old-python-version, a matrix written over several lines. A matcher earns trust by the ways it refuses to fire.

How it is proved

Run against 31 of my own repositories it found Python 3.10 in seventeen of them, forty days from the end of upstream support, and Node 20 in one, already 144 days past it — including its own CI, which is the point. 48 tests, standard library only.

Pythonstandard library only48 testsexit 1 for CI

People find this looking for

github actions deprecation checker, ubuntu-20.04 runner retired, actions/checkout v3 outdated, python 3.10 end of life CI, node 18 eol workflow, runner image retirement date.

If that is your week and you would rather someone else did it, write to hello@dkautomation.dev or open an issue.