Require Docutils 0.21 or greater (#14154)

tests/test_builders/test_build_html_image.py

@@ -75,12 +75,10 @@ def test_html_scaled_image_link(app: SphinxTestApp) -> None:
             context,
         )
     else:
-        # Docutils 0.21 adds a newline before the closing </a> tag
-        closing_space = '\n' if docutils.__version_info__[:2] >= (0, 21) else ''
         assert re.search(
             '\n<a class="reference internal image-reference" href="_images/img.png">'
             '<img alt="_images/img.png" src="_images/img.png" style="[^"]+" />'
-            f'{closing_space}</a>',
+            '\n</a>',
             context,
         )
 

tests/test_builders/test_build_linkcheck.py

@@ -15,7 +15,6 @@ from queue import Queue
 from typing import TYPE_CHECKING
 from unittest import mock
 
-import docutils
 import pytest
 from urllib3.poolmanager import PoolManager
 
@@ -177,11 +176,7 @@ def test_defaults(app: SphinxTestApp) -> None:
             'info': f'404 Client Error: Not Found for url: http://{address}/{filename}',
         }
 
-    accurate_linenumbers = docutils.__version_info__[:2] >= (0, 21)
-    image2_lineno = 12 if accurate_linenumbers else 13
-    assert rowsby[f'http://{address}/image2.png'] == _missing_resource(
-        'image2.png', image2_lineno
-    )
+    assert rowsby[f'http://{address}/image2.png'] == _missing_resource('image2.png', 12)
     # looking for '#top' and '#does-not-exist' not found should fail
     assert rowsby[f'http://{address}/#top']['info'] == "Anchor 'top' not found"
     assert rowsby[f'http://{address}/#top']['status'] == 'broken'

tests/test_builders/test_build_manpage.py

@@ -4,7 +4,6 @@ from __future__ import annotations
 
 from typing import TYPE_CHECKING
 
-import docutils
 import pytest
 
 from sphinx.builders.manpage import default_man_pages
@@ -65,25 +64,7 @@ def test_captioned_code_block(app: SphinxTestApp) -> None:
     app.build(force_all=True)
     content = (app.outdir / 'projectnamenotset.1').read_text(encoding='utf8')
 
-    if docutils.__version_info__[:2] < (0, 21):
-        expected = """\
-.sp
-caption \\fItest\\fP rb
-.INDENT 0.0
-.INDENT 3.5
-.sp
-.nf
-.ft C
-def ruby?
-    false
-end
-.ft P
-.fi
-.UNINDENT
-.UNINDENT
-"""
-    else:
-        expected = """\
+    expected = """\
 .sp
 caption \\fItest\\fP rb
 .INDENT 0.0