Include Python 3.9 again

Author: cbrnr

pyproject.toml

@@ -8,7 +8,7 @@ description = "The WFDB Python package: tools for reading, writing, and processi
 authors = [{name = "The Laboratory for Computational Physiology", email = "[email protected]"}]
 license = {text = "MIT License"}
 readme = "README.md"
-requires-python = ">= 3.10"
+requires-python = ">= 3.9"
 dependencies = [
     "numpy >= 1.26.4",
     "scipy >= 1.14.1",