Fix the issue that was preventing us from upgrading pytest. pytest does some manipulation of test packages that prevents `pkg_resources` from loading resources from them, but used to contain a workaround for the problem. That workaround was [removed](https://github.com/pytest-dev/pytest/issues/5392) in 4.6.0 as a performance enhancement when pytest switched from `pkg_resources` to `importlib-metadata` for its own entrypoint handling. This tripped up one of our test modules which defined classes that loaded templates from inside a test package. Moving these resources to the parent package fixes the problem. More and more, `pkg_resources` is being abandoned in favor of `importlib-metadata` and `importlib_resources` as they have a simpler design with much better performance. However, `importlib_resources` doesn't support loading files from any directory which isn't itself a Python package (and doesn't allow direct use of paths including directories within the package). Jinja2 chose a [different approach](https://github.com/pallets/jinja/pull/1082) that we may want to emulate in our resource handling. Also fixed usage of a removed `pytest.raises()` parameter and a bug in our configuration of the `common/lib` tests that became a problem after the upgrade.
Open edX -------- This is the root package for Open edX. The intent is that all importable code from Open edX will eventually live here, including the code in the lms, cms, and common directories. If you're adding a new Django app, place it in core/djangoapps. If you're adding utilities that require Django, place them in core/djangolib. If you're adding code that defines no Django models or views of its own but is widely useful, put it in core/lib. Note: All new code should be created in this package, and the legacy code will be moved here gradually. For now the code is not structured like this, and hence legacy code will continue to live in a number of different packages.