Rsconnect-python

Added
- Support for generating md5 file upload checksums, even if Python's `hashlib`
was configured for FIPS mode. The fallback uses the `usedforsecurity` option which is
available in Python 3.9 and later.

Added
- support for HTTPS_PROXY

Changed
- Environments are now introspected with `pip list --format=freeze` instead of `pip freeze`,
since the latter injects nonexistent paths into the requirements file when run in a conda environment.
This issue started occurring when pip 20.1 added support for PEP 610 metadata.
- Conda environments contain Conda-only versions of setuptools, which are now filtered out from requirements.txt for non-Conda environments.

Fixed
- Python 2 encoding error when using rsconnect-jupyter to publish a notebook containing binary data.
- Preserve more details when raising exceptions.