Fix linting issues found by flake8

Some are just `flake8` base checks, and some are found by `pydoclint`
(issues that `darglint` didn't catch):

* Line too long.
* Ununsed imports.
* Ambiguous variable name (`l` could be read as L or the number one with
  some fonts).
* Missing argument documentation.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

cookiecutter/local_extensions.py

@@ -230,7 +230,8 @@ def introduction(
 
 Welcome to repo-config Cookiecutter template!
 
-This template will help you to create a new repository for your project. You will be asked to provide some information about your project.
+This template will help you to create a new repository for your project. \
+You will be asked to provide some information about your project.
 
 Here is an explanation of what each variable is for and will be used for:
 

src/frequenz/repo/config/nox/config.py

@@ -235,7 +235,7 @@ def configure(
     # We need to make sure sessions are imported, otherwise they won't be visible to nox.
     if import_default_sessions:
         # pylint: disable=import-outside-toplevel,cyclic-import
-        from . import session as _
+        from . import session as _  # noqa: F401
 
     match conf:
         case Config():

src/frequenz/repo/config/setuptools/grpc_tools.py

@@ -13,7 +13,6 @@
 import pathlib as _pathlib
 import subprocess as _subprocess
 import sys as _sys
-import tomllib as _tomllib
 
 import setuptools as _setuptools
 import setuptools.command.build as _build_command

tests/integration/test_cookiecutter_generation.py

@@ -154,6 +154,7 @@ def _write_golden_file(golden_path: pathlib.Path, name: str, contents: str) -> i
     Args:
         golden_path: The path to the directory containing the golden files.
         name: The name of the golden file.
+        contents: The contents of the golden file to write.
 
     Returns:
         The number of bytes written.
@@ -259,9 +260,9 @@ def _filter_generation_output(
     the generated repo (a temporary directory).
     """
     stdout = b"\n".join(
-        l
-        for l in result.stdout.splitlines()
-        if not l.startswith((b"WARNING: The replay file's `_template` (",))
+        line
+        for line in result.stdout.splitlines()
+        if not line.startswith((b"WARNING: The replay file's `_template` (",))
     )
     return stdout, result.stderr