Cache Haskell builds

[mariari]

the CI takes over 15 minutes to run simple topics:

https://github.com/anoma/juvix-stdlib/actions/runs/11716928476/job/32635794732?pr=139

I'm leaving this issue here, for me to eventually investigate, as I should make a PR to address this:

      - name: Restore dependencies cache
        id: deps-cache
        uses: actions/[email protected]
        with:
          path: |
            deps
            _build
          key: |
            mix-${{ runner.os }}-${{ steps.beam.outputs.otp-version }}-${{ steps.beam.outputs.elixir-version }}-${{ hashFiles('**/mix.lock') }}
          restore-keys: |
            mix-${{ runner.os }}-${{ steps.beam.outputs.otp-version }}-${{ steps.beam.outputs.elixir-version }}-${{ hashFiles('**/mix.lock') }}

Here is the Anoma one

[mariari]

Upon review I'm unsure of what key do I restore it under, as I need to check the specific juvix-version

However Juvix falls under rolling releases, and I don't believe I can fix it upon the latest release tag for caching purposes.