Replace black and flake8 with ruff for linting and formatting

- Remove .flake8; add [tool.ruff] and [tool.ruff.format] config in pyproject.toml
  (line-length 120, excludes, ignore list, per-file-ignores, mccabe complexity)
- Update GitHub workflow lint job to run `ruff check .` and `ruff format --check .`
- Swap black and flake8 for ruff in requirements.txt and Pipfile
- Change capnp/__init__.py to ruff-style noqa comment
- Move max-complexity into [tool.ruff.lint.mccabe], lint options into [tool.ruff.lint]
- Add per-file-ignores for capnp/__init__.py (F401, F403, F405), remove inline noqa
- Run ruff format across codebase (24 files) for consistent style

scripts/capnp-json.py

@@ -48,9 +48,7 @@ def main():
     kwargs = vars(args)
     del kwargs["command"]
 
-    globals()[command](
-        **kwargs
-    )  # hacky way to get defined functions, and call function with name=command
+    globals()[command](**kwargs)  # hacky way to get defined functions, and call function with name=command
 
 
 main()