Merge pull request #11 in SSA/data from SSA-6324-df-pytest-docker to main

* commit '853abdcd':
  Fixing SHELL issue in Dockerfile
  SSA-6324: trying a different way of running setup
  SSA-6324: All tests pass when run locally. In Docker container, tests that exercise the CLI all fail, unable to find the "datafetcher" entry_point.
  SSA-6324: tests pass when run locally; some fail in Docker container. Committing what I've got so as not to lose it after tearing my hair out for a day and a half.
  SSA-6324: trhing to resolve package conflicts
  SSA-6324: 'docker build' is running into package conflicts
  SSA-6324: placate Pylint somewhat; this time -really- get rid of the properties file after the Docker image is built; look what Pathlib can do!
  SSA-6324: using Pathlib instead of os where possible. added a little more documentation.
  SSA-6324: pytest on datafetcher_test.py executes in a Docker container. capo properties file is copied to the docker build directory, then deleted.
  initial commit; datafetcher_test.py passes pytest