add Python 3.13 to pyproject.toml

Author: ndgrigorian

pyproject.toml

@@ -28,6 +28,7 @@ classifiers = [
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
   "Programming Language :: Python :: Implementation :: CPython",
   "Topic :: Software Development",
   "Topic :: Scientific/Engineering",