pyproject(trove classifiers) Drop Python 3.9

See also:
- https://devguide.python.org/versions/#:~:text=Release%20manager-,3.9,-PEP%20596
- https://peps.python.org/pep-0596/

Author: tony

pyproject.toml

@@ -16,7 +16,6 @@ classifiers = [
   "Operating System :: MacOS :: MacOS X",
   "Programming Language :: Python",
   "Programming Language :: Python :: 3",
-  "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",