Fix building from sdist

Specify build_meta backend because the default "setuptools.__legacy__" one
often has issues. PyPA-build for example tends to break with the
__legacy__ behavior, it also does not catch bugs with the SDist, while
the build_meta behavior does

See https://setuptools.readthedocs.io/en/latest/build_meta.html

Author: mayeut

pyproject.toml

@@ -1,2 +1,3 @@
 [build-system]
-requires = ["setuptools", "wheel", "scikit-build"]
+requires = ["setuptools>=42", "wheel", "scikit-build"]
+build-backend = "setuptools.build_meta"