[FEATURE] Skip tests CI for docs PR

[BewareMyPower]

Is your feature request related to a problem? Please describe. There is no need to run tests when the PR is only for docs.

Describe the solution you'd like Add the file change check script like what Pulsar's Github workflows do.

      - name: Check changed files
        id: check_changes
        run: echo "::set-output name=docs_only::${{ fromJSON(steps.changes.outputs.all_count) == fromJSON(steps.changes.outputs.docs_count) && fromJSON(steps.changes.outputs.docs_count) > 0 }}"

[BewareMyPower]

@timmyyuan Could you help with this issue?