Tests on pypy are failing due to missing file test/requirements.txt

[jaraco]

While testing other things, I noticed that the nox tests are failing for pypy:

nox > Running session pypy
nox > Creating virtual environment (virtualenv) using pypy in .nox/pypy
nox > python -m pip install -r test/requirements.txt
nox > Command python -m pip install -r test/requirements.txt failed with exit code 1:
ERROR: Could not open requirements file: [Errno 2] No such file or directory: 'test/requirements.txt'

[notice] A new release of pip available: 22.3.1 -> 23.1.2
[notice] To update, run: pip install --upgrade pip
nox > Session pypy failed.