Update WORKSPACE, setup.py, and requirements.txt to latest dp-accounting library release.
Update scipy version in setup.py.
Update version to 0.8.1.
PiperOrigin-RevId: 461944491
Also use the strip_prefix option to only pull in the accounting WORKSPACE, not the top-level Google DP project WORKSPACE. This allows us to align the import statements to work both when pulling in the `dp_acounting` dependency via Bazel and pip.
PiperOrigin-RevId: 459807060