pyproject.toml: Require python >= 3.8

Author: Matthias Koeppe

pyproject.toml

@@ -16,11 +16,11 @@ authors = [
 dependencies = [
     "Cython",
 ]
-requires-python = ">=3.6"
+requires-python = ">=3.8"
 readme = "README.md"
 license = {text = "GPLv3"}
 classifiers = [
-    "Development Status :: 2 - Pre-Alpha",
+    "Development Status :: 6 - Mature",
     "Intended Audience :: Science/Research",
     "License :: OSI Approved :: GNU General Public License v3 (GPLv3)",
     "Programming Language :: Cython",