Update `test.yml` with new github actions

I tagged you somewhere with the same comment, but I'm raising an issue here for posterity.

Might be worth it to update the test.yml file in ControlSystem.jl. See https://discourse.julialang.org/t/with-julia-actions-setup-julia-you-can-now-specify-lts-and-pre-named-versions/

The interesting parts would be to update to julia-actions/setup-julia@v2, actions/checkout@v4 and julia-actions/cache@v2. The v2 of cache speeds up the testing but requires this addition in the yml file:

    runs-on: ${{ matrix.os }} # new part just after this line:
    permissions: # needed for julia-actions/cache delete old caches that it has created
      actions: write
      contents: read

With v2 of setup-julia you can execute the tests on:

      matrix:
        version:
          - 'lts' # long-term support release
          - '1'   # latest stable 1.x release
          - 'pre' # latest stable prerelease
          # - 'nightly' # commented since noisy + 'pre' allows testing upcoming versions

IMO it covers large enough to see major issues for Julia version incompatibilities.

Open the test.yml workflow in ControlSystem.jl and compare its current Julia Actions, checkout, cache, permissions, and version-matrix settings with the issue requirements and linked Julia discourse discussion. Update the workflow entries described there, then run the repository's CI or test command to confirm the workflow remains valid across the requested Julia versions.