This message makes no sense to me:

The current project's supported Python range (>=3.12) is not compatible with some of the required packages Python requirement:
  - piprints requires Python <4.0,>=3.12, so it will not be satisfied for Python >=4.0

Because no versions of piprints match >4.0.1,<5.0.0
 and piprints (4.0.1) requires Python <4.0,>=3.12, piprints is forbidden.
So, because test depends on piprints (^4.0.1), version solving failed.

Long story. I am packaging a django app called piprints with this pyproject.toml:

[tool.poetry]
name = "piprints"
version = "4.0.1"
description = "preprint server"
authors = ["Emanuele Paolini <[email protected]>"]
readme = "README.md"

[tool.poetry.dependencies]
python = "^3.12"
django = "^5.1.5"
python-dotenv = "^1.0.1"
jinja2 = "^3.1.5"
requests = "^2.32.3"
python-dateutil = "^2.9.0.post0"
pillow = "^11.1.0"
argon2 = "^0.1.10"
argon2-cffi = "^23.1.0"


[build-system]
requires = ["poetry-core"]
build-backend = "poetry.core.masonry.api"

[tool.poetry.scripts]
manage = "piprints.manage:main"

I have pushed it on pypi. Then try to install it:

> poetry new test
Created package test in test
> cd test
> poetry add piprints
Creating virtualenv test in /home/emanuele/test/.venv
Using version ^4.0.1 for piprints

Updating dependencies
Resolving dependencies... (0.0s)

The current project's supported Python range (>=3.12) is not compatible with some of the required packages Python requirement:
  - piprints requires Python <4.0,>=3.12, so it will not be satisfied for Python >=4.0

Because no versions of piprints match >4.0.1,<5.0.0
 and piprints (4.0.1) requires Python <4.0,>=3.12, piprints is forbidden.
So, because test depends on piprints (^4.0.1), version solving failed.

  * Check your dependencies Python requirement: The Python requirement can be specified via the `python` or `markers` properties

    For piprints, a possible solution would be to set the `python` property to ">=3.12,<4.0"

    ,