[23.0] Fix create/install commands for conda 23.9.0

[nsoranzo]

The --experimental-solver option was removed.

This will fix the failing tests/test_cmd_test_conda.py::CmdTestCondaTestCase::test_local_conda_dependencies_version Planemo unit test (see e.g. https://github.com/galaxyproject/planemo/actions/runs/6458135476/job/17531176853 ), when an updated galaxy-tool-util package will be released.

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[mr-c]

Thank you @nsoranzo ! We also need this for cwltool and toil, as our tests are failing without it. When will the new version of the library be released?