python-poetry/poetry#3706
python-poetry/poetry#3870
python-poetry/poetry#4056

Poetry has a new install script, added in python-poetry/poetry#3706.
The old get-poetry.py install script is not compatible with Python 3.10,
so the new install-poetry.py script will be used.

Docker builds and GitHub Actions workflows will be updated to use
`POETRY_HOME=/opt/poetry` consistently.

As of Poetry 1.1.7, there may be complications in Docker when using
install-poetry.py without venvs (`POETRY_VIRTUALENVS_CREATE=false`).
While installing dependencies, the following error is frequently seen:

```text
OSError

Could not find a suitable TLS CA certificate bundle, invalid path:
/opt/poetry/venv/lib/python3.9/site-packages/certifi/cacert.pem

at /opt/poetry/venv/lib/python3.9/site-packages/requests/adapters.py:227
in cert_verify
```

Poetry may be incorrectly attempting to read from its virtualenv if it's
not respecting `POETRY_VIRTUALENVS_CREATE` (python-poetry/poetry#3870).
Downstream steps also do not respect `POETRY_VIRTUALENVS_CREATE`, so the
application does not run.

python-poetry/poetry#3706

Poetry has a new install script, install-poetry.py, which alters the
requirements for adding Poetry to `$PATH`. One simple way to add Poetry
to `$PATH` is to `export PATH=$HOME/.local/bin:$PATH`, which adds the
~/.local/bin directory (it's also used by pipx, so it's a good option)
to `$PATH`, then `export POETRY_HOME=$HOME/.local`, which tells Poetry
to install itself into the ~/.local/bin directory.

python-poetry/poetry#3706
python-poetry/poetry#3870
python-poetry/poetry#4056

Poetry has a new install script, added in python-poetry/poetry#3706.
The old get-poetry.py install script is not compatible with Python 3.10.
This commit will update the GitHub Actions workflow to use the new
install-poetry.py script, with `POETRY_HOME=/opt/poetry` for consistent
installs independent of user account, and will also update the workflow
to use a virtualenv and run commands with `poetry run` to avoid issues
with `POETRY_VIRTUALENVS_CREATE=false`.

As of Poetry 1.1.7, there may be complications with install-poetry.py
run without venvs (`POETRY_VIRTUALENVS_CREATE=false`). An error is seen:

```text
OSError

Could not find a suitable TLS CA certificate bundle, invalid path:
/opt/poetry/venv/lib/python3.9/site-packages/certifi/cacert.pem

at /opt/poetry/venv/lib/python3.9/site-packages/requests/adapters.py:227
in cert_verify
```

Poetry may be incorrectly attempting to read from its virtualenv if it's
not respecting `POETRY_VIRTUALENVS_CREATE` (python-poetry/poetry#3870).
Downstream steps also do not respect `POETRY_VIRTUALENVS_CREATE`, so the
application does not run. To avoid these issues, `poetry run` can be
prepended to commands to prompt Poetry to use its virtualenv.

Additionally, Poetry errors out with a `JSONDecodeError` when attempting
to install packages with Python 3.10 (python-poetry/poetry#4210). Python
3.10 support will be postponed until Poetry is compatible.

python-poetry/poetry#3706