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

- Add current folder to sys.path in setup.py

Fix importing versioneer when doing an isolated build/install with pip from sdist

- Add cmake build dependency

Author: mayeut

pyproject.toml

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

setup.py

@@ -1,6 +1,12 @@
 #!/usr/bin/env python
 
+import os
 import sys
+
+# Add current folder to path
+# This is required to import versioneer in an isolated pip build
+sys.path.append(os.path.dirname(os.path.abspath(__file__)))
+
 import versioneer
 
 from distutils.text_file import TextFile