Fix metadata

pyproject.toml

@@ -15,7 +15,7 @@ description = "Low-level CFFI bindings for Argon2"
 readme = { content-type = "text/markdown", file = "README.md" }
 authors = [{ name = "Hynek Schlawack", email = "[email protected]" }]
 requires-python = ">=3.7"
-license = { text = "MIT" }
+license = "MIT"
 keywords = ["password", "hash", "hashing", "security", "bindings", "cffi"]
 classifiers = [
     "Development Status :: 5 - Production/Stable",