fix label to US spelling

see https://github.com/openstreetmap/id-tagging-schema/pull/499#discussion_r967422124

interim/source_strings.yaml

@@ -1726,8 +1726,8 @@ en:
         label: Type
       license_classes:
         # license_classes=*
-        label: Driving License Classes
-        terms: '[translate with synonyms or related terms for ''Driving License Classes'', separated by commas]'
+        label: Classes of Driver’s License
+        terms: '[translate with synonyms or related terms for ''Classes of Driver’s License'', separated by commas]'
       lifeguard:
         # lifeguard=*
         label: Lifeguard