Simpler readme field

The README’s format is auto-detected from the extension:
`README.md` → GitHub-flavored Markdown

https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#readme

Author: DimitriPapadopoulos

pyproject.toml

@@ -15,7 +15,7 @@ dependencies = [
 requires-python = ">=3.9"
 
 description = "Foreign Function Interface for Python calling C code."
-readme = {file = "README.md", content-type = "text/markdown"}
+readme = "README.md"
 license = { file = "LICENSE" }
 classifiers = [
     "Programming Language :: Python",