Omit pypy3.7

Author: michalsta

pyproject.toml

@@ -10,7 +10,7 @@ name = "IsoSpecPy"
 dependencies = ["cffi"]
 description = "IsoSpecPy is a Python library for computing isotopic distributions of molecules."
 version = "2.3.0dev6"
-license-expression = "BSD-2-Clause"
+license = "BSD-2-Clause"
 license-files = ["LICENCE"]
 authors = [{name = "Michał Startek"}, {name = "Mateusz Łącki"}]
 readme = "README.md"
@@ -38,7 +38,7 @@ testpaths = ["tests/Python"]
 
 [tool.cibuildwheel]
 enable = ["pypy"]
-skip = ["cp36-*", "cp37-*"]
+skip = ["cp36-*", "cp37-*", "pp37-*"]
 test-command = "python -m pytest {project}/tests/Python"
 #test-sources = ["tests/Python"]
 test-extras = ["testing"]