When importing `debugpy`, `PYDEVD_IPYTHON_COMPATIBLE_DEBUGGING=1` should be set

[fabioz]

A new flag is available in pydevd which allows a user to step into library code without getting inside of IPython internals while doing so.

To make use of this, PYDEVD_IPYTHON_COMPATIBLE_DEBUGGING must be set to 1 in the os.environ prior to importing debugpy.

See: https://github.com/microsoft/debugpy/issues/869 for more information.