Add licence classifier [skip ci]

Author: jg-rp

pyproject.toml

@@ -13,6 +13,8 @@ keywords = []
 authors = [{ name = "James Prior", email = "jamesgr.prior@gmail.com" }]
 classifiers = [
   "Development Status :: 4 - Beta",
+  "Intended Audience :: Developers",
+  "License :: OSI Approved :: MIT License",
   "Programming Language :: Python",
   "Programming Language :: Python :: 3.8",
   "Programming Language :: Python :: 3.9",