Source version from dedicated module

fresnel/__init__.py

+from .version import __version__

fresnel/version.py

+__version__ = "0.1"

requirements.txt

-numpy >= 1.19.4
-scipy >= 1.5.2

setup.py

@@ -7,9 +7,14 @@ except ImportError:
       ' or you need to install the PEP 518 requirements in pyproject.toml yourself', file=sys.stderr)
   raise
 
+# following https://packaging.python.org/guides/single-sourcing-package-version/
+version = {}
+with open("fresnel/version.py") as fp:
+    exec(fp.read(), version)
+
 setup(
     name="fresnel",
-    version="0.1",
+    version=version['__version__'],
     author='Leon M. Lohse',
     author_email='llohse@uni-goettingen.de',
     url='https://gitlab.gwdg.de/irp/fresnel',