Update doctest GH workflow file
# What does this PR do?

Just as in other workflow files, this PR adds a step in doctest workflow file
```
      - name: Show installed libraries and their versions
        run: pip freeze
```
so we can quicly access this information whenever necessary, so faster debugging.

It took me some time to find the fix shown in  #21742
_The documentation is not available anymore as the PR was closed or merged._