[Feature request] convert to a PEP-621 standard `pyproject.toml`

[bolinocroustibat]

It would be nice if Stanza could convert requirements.txt to pyproject.toml not only for Poetry proprietary section in pyproject.toml, but also for all modern Python package managers (like PDM or pyflow) using pyproject.toml metadata PEP 621 standard.

Here what looks like a generic pyproject.toml, including a Poetry tool section:

[project]
name = "my-project"
version = "0.4.2"
description = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."
authors = [
    { name = "Foo Bar", email = "foo@bar.com" },
]
dependencies = [
    "colorama<1.0.0,>=0.4.4",
    "requests<3.0.0,>=2.25.1",
]
requires-python = ">=3.7,<4.0"
license = { text = "MIT" }

[tool.poetry]
name = "my-project"
version = "0.4.2"
description = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."
authors = ["Foor Bar"]

[tool.poetry.dependencies]
python = "^3.7"
colorama = "^0.4.4"
requests = "^2.25.1"

[tool.poetry.dev-dependencies]

[build-system]
requires = ["pdm-pep517"]
build-backend = "pdm.pep517.api"

Very nice project by the way, congrats! Hope it will inspire package managers using pyproject.toml!