update classifier

Author: ww-rm

pyproject.toml

@@ -10,6 +10,7 @@ authors = [
 description = "GM algorithms C extension for python."
 requires-python = ">=3.7"
 classifiers = [
+    "Programming Language :: C",
     "Programming Language :: Python :: 3",
     "License :: OSI Approved :: MIT License",
     "Operating System :: OS Independent",