Revert "Mark test_build_manpage as XFAIL following changes in Docutils master" (sphinx-doc#12734)

This reverts commit 1ed4ca7.

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>

Author: jfbu

tests/test_builders/test_build_manpage.py

@@ -7,8 +7,6 @@
 from sphinx.config import Config
 
 
-@pytest.mark.xfail(docutils.__version_info__[:2] > (0, 21),
-                   reason='Docutils has removed the reference key in master')
 @pytest.mark.sphinx('man')
 def test_all(app):
     app.build(force_all=True)
@@ -49,8 +47,6 @@ def test_man_make_section_directory(app):
     assert (app.outdir / 'man1' / 'projectnamenotset.1').exists()
 
 
-@pytest.mark.xfail(docutils.__version_info__[:2] > (0, 21),
-                   reason='Docutils has removed the reference key in master')
 @pytest.mark.sphinx('man', testroot='directive-code')
 def test_captioned_code_block(app):
     app.build(force_all=True)