add pypy classifier to pyproject.toml

Author: wbarnha

pyproject.toml

@@ -41,6 +41,8 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: Implementation :: CPython",
+    "Programming Language :: Python :: Implementation :: PyPy",
     "Operating System :: POSIX",
     "Operating System :: Microsoft :: Windows",
     "Operating System :: MacOS :: MacOS X",