Switched to use SPDX license classifier

Author: agronholm

pyproject.toml

@@ -10,11 +10,10 @@ name = "anyio"
 description = "High level compatibility layer for multiple asynchronous event loop implementations"
 readme = "README.rst"
 authors = [{name = "Alex Grönholm", email = "alex.gronholm@nextday.fi"}]
-license = {text = "MIT"}
+license = "MIT"
 classifiers = [
     "Development Status :: 5 - Production/Stable",
     "Intended Audience :: Developers",
-    "License :: OSI Approved :: MIT License",
     "Framework :: AnyIO",
     "Typing :: Typed",
     "Programming Language :: Python",