Move dateset to rare

Although it's hardly a word, it appears to have been added
to the aspell dictionary:
#2897

Author: DimitriPapadopoulos

codespell_lib/data/dictionary.txt

@@ -11504,8 +11504,6 @@ datecreatedd->datecreated
 datection->detection
 datections->detections
 datee->date
-dateset->dataset
-datesets->datasets
 datset->dataset
 datsets->datasets
 daty->data, date,

codespell_lib/data/dictionary_rare.txt

@@ -58,6 +58,8 @@ creche->crèche
 cristal->crystal
 crufts->cruft
 curios->curious
+dateset->dataset
+datesets->datasets
 dealign->dealing
 deffer->differ, defer,
 degrate->degrade