DEV: remove mccabe code complexity check from the ruff config

It has given issues a couple of times that take time to resolve,
and the complaints it emits seem unjustified at least in some
cases. So remove it - relying on code review is fine here.

mesonpy/__init__.py

@@ -603,7 +603,7 @@ def _string_or_strings(value: Any, name: str) -> List[str]:
 class Project():
     """Meson project wrapper to generate Python artifacts."""
 
-    def __init__(  # noqa: C901
+    def __init__(
         self,
         source_dir: Path,
         build_dir: Path,

pyproject.toml

@@ -82,7 +82,6 @@ extend-ignore = [
 select = [
   'B',       # flake8-bugbear
   'C4',      # flake8-comprehensions
-  'C9',      # mccabe
   'E',       # pycodestyle
   'F',       # pyflakes
   'W',       # pycodestyle
@@ -92,10 +91,6 @@ exclude = [
   'docs/conf.py',
 ]
 
-[tool.ruff.mccabe]
-max-complexity = 12
-
-
 [tool.isort]
 lines_between_types = 1
 lines_after_imports = 2