Set up ruff so that test files have at least some linting (#10399)

Alternative implementation for #7908.

In this PR:
- set up ruff in CI (add to `tox.ini`, mark dep in `certbot/setup.py`)
- add a `ruff.toml` that ignores particularly annoying errors. I think
line length isn't actually necessary to set with this workflow since
we're not checking it but putting it there for future usage.
- either fix or ignore the rest of the errors that come with the default
linting configuration. fixed errors are mostly unused variables. ignored
are usually where we're doing weird import things for a specific reason.

certbot-apache/src/certbot_apache/_internal/tests/configurator_test.py

@@ -1245,7 +1245,7 @@ class MultipleVhostsTest(util.ApacheTest):
 
     def test_deploy_cert_no_mod_ssl(self):
         # Create
-        ssl_vhost = self.config.make_vhost_ssl(self.vh_truth[0])
+        self.config.make_vhost_ssl(self.vh_truth[0])
         self.config.parser.modules["socache_shmcb_module"] = None
         self.config.prepare_server_https = mock.Mock()
 

certbot-apache/src/certbot_apache/_internal/tests/parsernode_configurator_test.py

@@ -1,4 +1,5 @@
 """Tests for ApacheConfigurator for AugeasParserNode classes"""
+import importlib
 import sys
 import unittest
 from unittest import mock
@@ -7,10 +8,10 @@ import pytest
 
 from certbot_apache._internal.tests import util
 
-try:
-    import apacheconfig
+
+if importlib.util.find_spec('apacheconfig'):
     HAS_APACHECONFIG = True
-except ImportError:  # pragma: no cover
+else:  # pragma: no cover
     HAS_APACHECONFIG = False
 
 

certbot-apache/src/certbot_apache/_internal/tests/parsernode_test.py

@@ -112,12 +112,12 @@ def test_dummy():
         dirty=False,
         filepath="/some/random/path"
     )
-    dummydirective = DummyDirectiveNode(
+    dummydirective = DummyDirectiveNode( # noqa: F841
         name="Name",
         ancestor=None,
         filepath="/another/path"
     )
-    dummycomment = DummyCommentNode(
+    dummycomment = DummyCommentNode( # noqa: F841
         comment="Comment",
         ancestor=dummyblock,
         filepath="/some/file"