DOC: Added whatsnew for GH-29174 (#29256)

ci/code_checks.sh

@@ -171,10 +171,6 @@ if [[ -z "$CHECK" || "$CHECK" == "patterns" ]]; then
     invgrep -R --include="*.py" --include="*.pyx" --include="*.rst" -E "\.\. (autosummary|contents|currentmodule|deprecated|function|image|important|include|ipython|literalinclude|math|module|note|raw|seealso|toctree|versionadded|versionchanged|warning):[^:]" ./pandas ./doc/source
     RET=$(($RET + $?)) ; echo $MSG "DONE"
 
-    MSG='Check that the deprecated `assert_raises_regex` is not used (`pytest.raises(match=pattern)` should be used instead)' ; echo $MSG
-    invgrep -R --exclude=*.pyc --exclude=testing.py --exclude=test_util.py assert_raises_regex pandas
-    RET=$(($RET + $?)) ; echo $MSG "DONE"
-
     # Check for the following code in testing: `unittest.mock`, `mock.Mock()` or `mock.patch`
     MSG='Check that unittest.mock is not used (pytest builtin monkeypatch fixture should be used instead)' ; echo $MSG
     invgrep -r -E --include '*.py' '(unittest(\.| import )mock|mock\.Mock\(\)|mock\.patch)' pandas/tests/

doc/source/whatsnew/v1.0.0.rst

@@ -255,6 +255,7 @@ or ``matplotlib.Axes.plot``. See :ref:`plotting.formatters` for more.
 - Removed the previously deprecated ``IntervalIndex.from_intervals`` in favor of the :class:`IntervalIndex` constructor (:issue:`19263`)
 - Ability to read pickles containing :class:`Categorical` instances created with pre-0.16 version of pandas has been removed (:issue:`27538`)
 - Removed the previously deprecated ``reduce`` and ``broadcast`` arguments from :meth:`DataFrame.apply` (:issue:`18577`)
+- Removed the previously deprecated ``assert_raises_regex`` function in ``pandas.util.testing`` (:issue:`29174`)
 -
 
 .. _whatsnew_1000.performance: