[3.12] Fix grammar and improve clarity for an deprecation message. (GH-105457) (#105458)

Author: miss-islington

Modules/itertoolsmodule.c

@@ -98,8 +98,8 @@ class itertools.pairwise "pairwiseobject *" "clinic_state()->pairwise_type"
 #define ITERTOOL_PICKLE_DEPRECATION                                           \
     if (PyErr_WarnEx(                                                         \
             PyExc_DeprecationWarning,                                         \
-            "Itertool pickle/copy/deepcopy support "                          \
-            "will be removed in a Python 3.14.", 1) < 0) {                    \
+            "Pickle, copy, and deepcopy support will be "                     \
+            "removed from itertools in Python 3.14.", 1) < 0) {               \
         return NULL;                                                          \
     }