doc(nitpick): ignore scikit-learn metadata routing

Adds a few classes to ignore that cause problems since updating sklearn.

doc/nitpick-exceptions.txt

@@ -12,3 +12,8 @@ py:class defaultdict
 py:class WorkerState
 py:class deque
 py:class sklearn.BaseEstimator
+
+# sklearn >= 1.3: issue with docs of metadata routing
+py:class True
+py:class False
+py:class default=sklearn.utils.metadata_routing.UNCHANGED