Address some deprecation warnings

pytest.ini

@@ -0,0 +1,5 @@
+[pytest]
+filterwarnings =
+    error
+    # docutils planned change in 0.21 without clear solution yet
+    ignore:The frontend.*:DeprecationWarning

setup.cfg

@@ -16,7 +16,7 @@ author_email = openstack-discuss@lists.openstack.org
 maintainer = PyCQA
 maintainer_email = code-quality@python.org
 license = Apache 2.0
-license_file = LICENSE
+license_files = LICENSE
 classifiers =
     Development Status :: 5 - Production/Stable
 
@@ -60,7 +60,9 @@ include_package_data = True
 zip_safe = False
 # These are required in actual runtime:
 install_requires =
-    docutils
+    # Ceiled due to DeprecationWarning: The frontend.OptionParser class will be
+    # replaced by a subclass of argparse.ArgumentParser in Docutils 0.21 or later.
+    docutils>=0.19,<0.21
     restructuredtext-lint>=0.7
     stevedore
     tomli; python_version < '3.11'

src/doc8/checks.py

@@ -160,7 +160,7 @@ def extract_lines(node, start_line):
 
         def gather_lines(node):
             lines = []
-            for n in node.traverse(include_self=True):
+            for n in node.findall(include_self=True):
                 lines.extend(extract_lines(n, find_line(n)))
             return lines
 

src/doc8/utils.py

@@ -57,7 +57,7 @@ def path_ignorable(path):
 
 
 def filtered_traverse(document, filter_func):
-    for n in document.traverse(include_self=True):
+    for n in document.findall(include_self=True):
         if filter_func(n):
             yield n
 

tox.ini

@@ -6,7 +6,7 @@ isolated_build = True
 [testenv]
 deps =
   -r{toxinidir}/test-requirements.txt
-commands = pytest {posargs}
+commands = pytest -v {posargs}
 whitelist_externals =
   rm
   sh