Store license identifier inside the License-Expression metadata field (#4479)

Author: cdce8p

CHANGES.md

@@ -22,6 +22,9 @@
 
 <!-- Changes to how Black is packaged, such as dependency requirements -->
 
+- Store license identifier inside the `License-Expression` metadata field, see
+  [PEP 639](https://peps.python.org/pep-0639/). (#4479)
+
 ### Parser
 
 <!-- Changes to the parser or to version autodetection -->

pyproject.toml

@@ -33,7 +33,7 @@ build-backend = "hatchling.build"
 [project]
 name = "black"
 description = "The uncompromising code formatter."
-license = { text = "MIT" }
+license = "MIT"
 requires-python = ">=3.9"
 authors = [
   { name = "Łukasz Langa", email = "[email protected]" },