Update license

pyproject.toml

@@ -50,7 +50,6 @@ requires-python = ">=3.9"
 # that contains the license
 # https://packaging.python.org/en/latest/specifications/core-metadata/#license
 #license = { file = "LICENSE" }
-license = "GPL-3.0-or-later"
 
 # This field adds keywords for your project which will appear on the
 # project page. What does your project relate to?
@@ -168,6 +167,7 @@ stone-gui = "stone.__main__:main"
 # If there are data files included in your packages that need to be
 # installed, specify them here.
 package-dir = { "" = "src" }
+license-files = ["LICENSE"]
 
 [tool.setuptools.dynamic]
 version = { attr = "stone.package.__version__" }