Need at least pip 21.3 for an editable install (-e)

Author: peterjc

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ['pip>=20.3', 'setuptools>=61', 'wheel']
+requires = ['pip>=21.3', 'setuptools>=61', 'wheel']
 build-backend = 'setuptools.build_meta'
 
 [project]