output a dictionary of tool versions

[mhanberg]

Description

It would be useful to output the versions of each tool that is detected in the .mise.toml/.tool-versions file to use later on in the workflow, while still keeping them isolated to one place.

One example is setting a cache key based on the language version, elixir below

      - uses: actions/cache@v3
        with:
          path: |
            deps
            _build
          key: ${{ runner.os }}-mix-${{matrix.otp}}-${{matrix.elixir}}-${{ hashFiles('**/mix.lock') }}
          restore-keys: |
            ${{ runner.os }}-mix-${{matrix.otp}}-${{matrix.elixir}}-

I believe a workaround is to just hash the .mise.toml file, and whenever you change it, it will bust the cache, but that would bust it even if you change a version of an unrelated (to this cache) tool.