[Python] Error `ModuleNotFoundError: No module named 'Cython'` encountered when using `uv...

I am using uv as my package manager in building a python package of my own. Actually I switched from the typical setuptools to uv because I found that uv is fast and great. However when I run uv build just as I have used python -m build in using setuptools, I encountered an error saying ModuleNotFoundError: No module named 'Cython'.

Below is my project's pyproject.toml file, in which numpy is one of the dependencies. I don't know whether it is numpy that causes the problem. I have tried uv tool install cython and uv add --dev cython, but neither solved the problem.

[project]
name = "fantazia"
version = "0.0.1"
authors = [{ name = "F. X. P.", email = "vanleefxp@gmail.com" }]
description = "A package for math-based music theory computation."
readme = "README.md"
requires-python = ">=3.12"
classifiers = [
"Programming Language :: Python :: 3",
"Operating System :: OS Independent",
"License :: OSI Approved :: MIT License",
]
keywords = ["music"]
dependencies = [
"bidict>=0.23.1",
"numpy>=2.2.4",
"pyrsistent>=0.20.0",
"scikit-learn>=1.6.1",
"scipy>=1.15.2",
"sortedcontainers>=2.4.0",
]

[project.urls]
Homepage = "https://github.com/vanleefxp/fantazia"
Issues = "https://github.com/vanleefxp/fantazia/issues"

[project.optional-dependencies]
m21 = ["music21>=9.3.0"]

[dependency-groups]
dev = [
"cython>=3.0.12",
]


And below is the full error message:

Building source distribution...
Traceback (most recent call last):
File "<string>", line 14, in <module>
requires = get_requires_for_build({})
File "D:\AppData\uv\cache\builds-v0\.tmpl3mxVT\Lib\site-packages\setuptools\build_meta.py", line 337, in get_requires_for_build_sdist
return self._get_build_requires(config_settings, requirements=[])
~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "D:\AppData\uv\cache\builds-v0\.tmpl3mxVT\Lib\site-packages\setuptools\build_meta.py", line 304, in _get_build_requires
self.run_setup()
~~~~~~~~~~~~~~^^
File "D:\AppData\uv\cache\builds-v0\.tmpl3mxVT\Lib\site-packages\setuptools\build_meta.py", line 522, in run_setup
super().run_setup(setup_script=setup_script)
~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "D:\AppData\uv\cache\builds-v0\.tmpl3mxVT\Lib\site-packages\setuptools\build_meta.py", line 320, in run_setup
exec(code, locals())
~~~~^^^^^^^^^^^^^^^^
File "<string>", line 2, in <module>
ModuleNotFoundError: No module named 'Cython'
× Failed to build `D:\New Homeland\Programming\Python\Fantazia`
├─▶ The build backend returned an error
╰─▶ Call to `setuptools.build_meta:__legacy__.build_sdist` failed (exit code: 1)
hint: This usually indicates a problem with the package or the build environment.

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