Replace distutils.versions.LooseVersion by packaging.version.Version

Distutils module are now deprecated and will be removed in Python 3.12.
This replaces it by packaging module and reduces the dependency to it.

refs: #9820

tests/test_build_html.py

@@ -10,13 +10,13 @@
 
 import os
 import re
-from distutils.version import LooseVersion
 from itertools import chain, cycle
 from unittest.mock import ANY, call, patch
 
 import pygments
 import pytest
 from html5lib import HTMLParser
+from packaging import version
 
 from sphinx.builders.html import validate_html_extra_path, validate_html_static_path
 from sphinx.errors import ConfigError
@@ -30,6 +30,9 @@ else:
     FIGURE_CAPTION = ".//figure/figcaption/p"
 
 
+PYGMENTS_VERSION = version.parse(pygments.__version__).release
+
+
 ENV_WARNINGS = """\
 %(root)s/autodoc_fodder.py:docstring of autodoc_fodder.MarkupError:\\d+: \
 WARNING: Explicit markup ends without a blank line; unexpected unindent.
@@ -1576,8 +1579,7 @@ def test_html_codeblock_linenos_style_table(app):
     app.build()
     content = (app.outdir / 'index.html').read_text()
 
-    pygments_version = tuple(LooseVersion(pygments.__version__).version)
-    if pygments_version >= (2, 8):
+    if PYGMENTS_VERSION >= (2, 8):
         assert ('<div class="linenodiv"><pre><span class="normal">1</span>\n'
                 '<span class="normal">2</span>\n'
                 '<span class="normal">3</span>\n'
@@ -1592,8 +1594,7 @@ def test_html_codeblock_linenos_style_inline(app):
     app.build()
     content = (app.outdir / 'index.html').read_text()
 
-    pygments_version = tuple(LooseVersion(pygments.__version__).version)
-    if pygments_version > (2, 7):
+    if PYGMENTS_VERSION > (2, 7):
         assert '<span class="linenos">1</span>' in content
     else:
         assert '<span class="lineno">1 </span>' in content