Poetry fails to recognize dynamic URL that is environment variable in TOML

[MattPPlumb]

Using poetry 1.8.3 and poetry-source-env 2.0.1

pyproject.toml includes the following content:

[tool.poetry-source-venv]
env = false
toml = true

[[tool.poetry.source]]
name = "private-pypi"
url = "${PRIVATE_PYPI_URL}"
priority = "explicit"

Created environment variable: PRIVATE_PYPI_URL with proper url to private pypi server.

When running poetry install the following response is received:

The Poetry configuration is invalid:
  - data.source[0].url must be uri