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

examples/async_ssl_calculator_server.py

@@ -112,9 +112,7 @@ class CalculatorImpl(calculator_capnp.Calculator.Server):
 
 
 def parse_args():
-    parser = argparse.ArgumentParser(
-        usage="""Runs the server bound to the given address/port ADDRESS. """
-    )
+    parser = argparse.ArgumentParser(usage="""Runs the server bound to the given address/port ADDRESS. """)
 
     parser.add_argument("address", help="ADDRESS:PORT")
 
@@ -138,14 +136,10 @@ async def main():
     # Handle both IPv4 and IPv6 cases
     try:
         print("Try IPv4")
-        server = await capnp.AsyncIoStream.create_server(
-            new_connection, host, port, ssl=ctx, family=socket.AF_INET
-        )
+        server = await capnp.AsyncIoStream.create_server(new_connection, host, port, ssl=ctx, family=socket.AF_INET)
     except Exception:
         print("Try IPv6")
-        server = await capnp.AsyncIoStream.create_server(
-            new_connection, host, port, ssl=ctx, family=socket.AF_INET6
-        )
+        server = await capnp.AsyncIoStream.create_server(new_connection, host, port, ssl=ctx, family=socket.AF_INET6)
 
     async with server:
         await server.serve_forever()