Unable to install testflinger-cli to env/bin after commit f2da85c6

[Po-Hsu Lin]

It looks like testflinger-cli from https://github.com/canonical/testflinger-cli cannot be installed properly with the steps described in README.md

# Steps to reproduce:
git clone https://github.com/canonical/testflinger-cli.git
cd testflinger-cli
virtualenv -p python3 env
. env/bin/activate
pip install .

# Check if testflinger-cli exists in env/bin
ls env/bin

Here is the output from `pip install .`:
Processing /home/maas/testflinger-cli-gh
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
  Installing backend dependencies ... done
  Preparing metadata (pyproject.toml) ... done
Building wheels for collected packages: UNKNOWN
  Building wheel for UNKNOWN (pyproject.toml) ... done
  Created wheel for UNKNOWN: filename=UNKNOWN-0.0.0-py3-none-any.whl size=961 sha256=10b2f4e8453c63e4b1c74112e937f1a95409a04a445a6f76b8d95c472a113f14
  Stored in directory: /home/maas/.cache/pip/wheels/98/a5/4d/7d361cf249e09f829444a6253c7e04aa5209443b9792c1e346
Successfully built UNKNOWN
Installing collected packages: UNKNOWN
Successfully installed UNKNOWN-0.0.0

Bisect shows:
f2da85c65ff6ba5cfae698db7d8174f402789986 is the first bad commit
commit f2da85c65ff6ba5cfae698db7d8174f402789986
Author: Paul Larson <email address hidden>
Date: Fri Feb 10 10:16:07 2023 -0600

    Convert from setup.py to pyproject

[Paul Larson (pwlars)]

Please refile this on https://github.com/canonical/testflinger if it still fails there, but I'm pretty sure it should work. Everything has moved to a monorepo there instead.