Update test.yml with new github actions

[franckgaga]

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.