How about changing interpretation of version string

Many users who wants use 3.0.x write ruby-version: 3.0 by mistake.

3.0 interpreted as 3 on GitHub Actions.

For example, following workflow step prints 3 only.

        env:
          env_var: 3.0
        run: |
          set -x
          echo ${env_var}

So I propose changing the meaning of 3 (and 3.0 on workflow files) use 3.0.x, and 3.x (or something) use latest 3.x.x.

After this change, many users can write 3.0 intentionally, and some (probably less) users who want use latest 3.x.x can write 3.x or something instead.

Start by tracing how the ruby-version input is interpreted in GitHub Actions workflow files, using the reported 3.0 environment-value example as the motivating case. Define and verify the intended meanings for 3, 3.0, and 3.x, including the compatibility impact on existing workflows.