add valid matching pypi license classifier

Author: andreiosg

pyproject.toml

@@ -23,7 +23,7 @@ classifiers = [
     "Development Status :: 4 - Beta",
     "Intended Audience :: Developers",
     "Topic :: Software Development :: Build Tools",
-    "License :: None",
+    "License :: OSI Approved :: BSD License",
     "Programming Language :: Python :: 3",
     "Framework :: Robot Framework",
     "Framework :: Robot Framework :: Library",