Remove setup.cfg

* flake8 doesn't support pyproject.toml, so move to .flake8
* coverage requires the toml extra to read pyproject.toml, so add that
* mypy supports it by default

Remove since we want to get rid of setup.py, so might as well remove
setup.cfg as well.

.flake8

@@ -0,0 +1,5 @@
+[flake8]
+ignore=E402,E741
+builtins=buffer,unichr
+max-line-length = 100
+exclude = build

pyproject.toml

@@ -17,10 +17,40 @@ mypy = {version = "1.8.0", markers = "platform_python_implementation != 'PyPy'"}
 flake8 = "^7.0.0"
 Sphinx = "^6.2.1"
 sphinx-rtd-theme = "^2.0.0"
-coverage = "^7.2.3"
+coverage = {extras = ["toml"], version = "^7.2.3"}
 sphinx-autobuild = "^2021.3.14"
 setuptools = "^69.0.3"
 
+[tool.coverage.run]
+include = [
+    "cairo/*",
+    "tests/*"
+]
+
+[tool.mypy]
+disallow_any_unimported = true
+disallow_any_expr = true
+disallow_any_generics = true
+disallow_subclassing_any = true
+disallow_untyped_calls = true
+disallow_untyped_defs = true
+check_untyped_defs = true
+warn_return_any = true
+no_implicit_optional = true
+disallow_any_decorated = true
+disallow_any_explicit = false
+strict_optional = true
+follow_imports = "silent"
+exclude = ["^(examples/|build|docs/)"]
+
+[[tool.mypy.overrides]]
+module = "setup"
+ignore_errors = true
+
+[[tool.mypy.overrides]]
+module = "tests.*"
+ignore_errors = true
+
 [tool.meson-python.args]
 setup = ["-Dwheel=true", "-Dtests=false"]