Check workflows for issues during CI

[jplomas]

This PR adds an Actionlint workflow to validate GH actions as per #1866

This is an updated version of PR #1880, taking into account the discussion on that contribution.

Actionlint checking would have protected against the changes fixed in #1869 and #1902, e.g. (for the latter):

➜ actionlint .github/workflows/*.yml
.github/workflows/linux.yml:176:5: unexpected key "libjade-build" for "job" section. expected one of "concurrency", "container", "continue-on-error", "defaults", "env", "environment", "if", "name", "needs", "outputs", "permissions", "runs-on", "secrets", "services", "steps", "strategy", "timeout-minutes", "uses", "with" [syntax-check]
    |
176 |     libjade-build:
    |     ^~~~~~~~~~~~~~
.github/workflows/linux.yml:187:84: property "libjade-build" is not defined in object type {cmake_args: string; container: string; name: string; pytest_args: string; runner: string} [expression]
    |
187 |         run: mkdir build && cd build && cmake -GNinja ${{ matrix.CMAKE_ARGS }} ${{ matrix.libjade-build }} .. && cmake -LA -N ..
    |                                                                                    ^~~~~~~~~~~~~~~~~~~~
.github/workflows/platforms.yml:17:11: error while parsing reusable workflow "./.github/workflows/linux.yml": "workflow_call" event trigger is not found in "on:" at line:6, column:5 [workflow-call]
   |
17 |     uses: ./.github/workflows/linux.yml
   |           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* [ ] Does this PR change the input/output behaviour of a cryptographic algorithm (i.e., does it change known answer test values)? (If so, a version bump will be required from x.y.z to x.(y+1).0.)
* [ ] Does this PR change the list of algorithms available -- either adding, removing, or renaming? Does this PR otherwise change an API? (If so, PRs in fully supported downstream projects dependent on these, i.e., oqs-provider will also need to be ready for review and merge by the time this is merged.)

[jplomas]

@SWilson4 should this PR trigger .github/workflows/pr.yml to run automatically?

[SWilson4]

@SWilson4 should this PR trigger .github/workflows/pr.yml to run automatically?

I was expecting it to, even on a PR from a fork... let me see if I can figure out what's going on.

[SWilson4]

Ironically, it looks like an invalid workflow error: https://github.com/open-quantum-safe/liboqs/actions/runs/10789716344/workflow

[jplomas]

Well spotted... got as far as seeing it was a checkout problem. Hopefully that's sorted it.

[SWilson4]

LGTM. Thanks very much for this improvement, JP!

[baentsch]

I'm not asked for review but did regardless and also think it's good to merge. Thanks, @jplomas ! Please consider contributing the same logic to oqsprovider. Same statement & wish regarding your CI improvements @SWilson4 .

[SWilson4]

Merging! Thanks again for the contribution, @jplomas.