maturin build not working with older python versions

Question

I created anaconda environment

$ python --version
Python 3.7.13
$ pip --version
pip 22.2.2 from C:\tools\miniconda3\envs\py37\lib\site-packages\pip (python 3.7)

In pyproject.toml I have requires-python = ">=3.7"

[build-system]
requires = ["maturin>=0.13,<0.14"]
build-backend = "maturin"

[project]
name = "ecc_py"
requires-python = ">=3.7"
classifiers = [
    "Programming Language :: Rust",
    "Programming Language :: Python :: Implementation :: CPython",
    "Programming Language :: Python :: Implementation :: PyPy",
]

I run maturin build

$ maturin build --release  
Finished release [optimized] target(s) in 10.73s
 Built wheel for CPython 3.10 to C:\Users\Aleksander\source\repos\Rust\ecc\target\wheels\ecc_py-0.1.0-cp310-none-win_amd64.whl

but then the wheel fails to install

$ pip install ..\target\wheels\ecc_py-0.1.0-cp310-none-win_amd64.whl
ERROR: ecc_py-0.1.0-cp310-none-win_amd64.whl is not a supported wheel on this platform.

It installs successfully in conda environment python=3.10. What am I doing wrong? It should be compatible with older versions as well. It works when running

$ maturin develop
 Built wheel for CPython 3.7 to C:\Users\ALEKSA~1\AppData\Local\Temp\.tmpXTZvEE\ecc_py-0.1.0-cp37-none-win_amd64.whl
  Installed ecc-py-0.1.0

Answer 1

So it found out it works with -i flag

$ maturin build --release -i python
    Finished release [optimized] target(s) in 6.33s
 Built wheel for CPython 3.7 to C:\Users\Aleksander\source\repos\Rust\ecc\target\wheels\ecc_py-0.1.0-cp37-none-win_amd64.whl

I have no clue why it wouldn't work without it though.