packaging: switch to pyproject.toml

Prefer pyproject.toml over setup.cfg for packaging. The changes in the
build results are minimal, only PKG-INFO changes:

-Home-page: https://github.com/jnikula/hawkmoth
-Author: Jani Nikula
-Author-email: [email protected]
+Author-email: Jani Nikula <[email protected]>
 License: BSD-2-Clause
+Project-URL: Homepage, https://github.com/jnikula/hawkmoth

Flake8 configuration remains in setup.cfg.

pyproject.toml

@@ -4,6 +4,58 @@ requires = [
     "wheel"
 ]
 build-backend = "setuptools.build_meta"
+
+[project]
+name = "hawkmoth"
+dynamic = ["version"]
+description = "Hawkmoth - Sphinx Autodoc for C"
+readme = {file = "README.rst", content-type = "text/x-rst"}
+license = {text = "BSD-2-Clause"}
+requires-python = "~=3.8"
+authors = [
+    {name = "Jani Nikula", email = "[email protected]"},
+]
+keywords = [
+    "autodoc",
+    "c",
+    "documentation",
+    "python",
+    "sphinx",
+]
+classifiers = [
+    "Development Status :: 4 - Beta",
+    "Framework :: Sphinx :: Extension",
+    "Intended Audience :: Developers",
+    "License :: OSI Approved :: BSD License",
+    "Operating System :: OS Independent",
+    "Programming Language :: Python :: 3",
+    "Topic :: Documentation :: Sphinx",
+    "Topic :: Software Development :: Documentation",
+]
+dependencies = [
+    "sphinx >= 3",
+]
+
+[project.optional-dependencies]
+dev = [
+    "flake8",
+    "pytest",
+    "pytest-cov",
+    "pytest-xdist",
+    "restructuredtext_lint",
+    "strictyaml",
+]
+
+[project.scripts]
+hawkmoth = "hawkmoth.__main__:main"
+
+[project.urls]
+Homepage = "https://github.com/jnikula/hawkmoth"
+Documentation = "https://jnikula.github.io/hawkmoth/stable/"
+
+[tool.setuptools.dynamic]
+version = {file = ["src/hawkmoth/VERSION"]}
+
 [tool.pytest.ini_options]
 minversion = "6.0"
 addopts = "--strict-markers"

setup.cfg

@@ -1,64 +1,3 @@
-[metadata]
-name = hawkmoth
-version = file: src/hawkmoth/VERSION
-author = Jani Nikula
-author_email = [email protected]
-description = Hawkmoth - Sphinx Autodoc for C
-long_description = file: README.rst
-long_description_content_type = text/x-rst
-license = BSD-2-Clause
-license_files = LICENSE
-url = https://github.com/jnikula/hawkmoth
-project_urls =
-    Documentation = https://jnikula.github.io/hawkmoth/stable/
-keywords =
-    autodoc
-    c
-    documentation
-    python
-    sphinx
-classifiers =
-    Development Status :: 4 - Beta
-    Framework :: Sphinx :: Extension
-    Intended Audience :: Developers
-    License :: OSI Approved :: BSD License
-    Operating System :: OS Independent
-    Programming Language :: Python :: 3
-    Topic :: Documentation :: Sphinx
-    Topic :: Software Development :: Documentation
-
-[options]
-python_requires = ~=3.8
-install_requires =
-    sphinx >= 3
-    # clang, depend on distro packaging
-package_dir=
-    =src
-packages =
-    hawkmoth
-    hawkmoth.ext
-    hawkmoth.ext.javadoc
-    hawkmoth.ext.napoleon
-    hawkmoth.ext.transformations
-    hawkmoth.util
-
-[options.extras_require]
-dev =
-    flake8
-    pytest
-    pytest-cov
-    pytest-xdist
-    restructuredtext_lint
-    strictyaml
-
-[options.package_data]
-hawkmoth =
-    VERSION
-
-[options.entry_points]
-console_scripts =
-    hawkmoth = hawkmoth.__main__:main
-
 [flake8]
 extend-ignore = E302,E305
 max-line-length = 100