Fix week end date calculation

aleksis/apps/alsijil/assets/components/coursebook/LessonDocumentations.vue

@@ -248,8 +248,8 @@
           var start_date = new Date(((lesson_date.getDay() || 7) !== 1) ? lesson_date.setHours(-24 * (lesson_date.getDay() - 1)) : lesson_date)
         }
         let end_date = new Date(start_date)
-        end_date.setDate(end_date.getDate() + 7)
-        return $d(start_date, "short") + " - " + $d(end_date, "short") + ", " + this.$root.django.gettext('CW') + " " + item.week
+        end_date.setDate(end_date.getDate() + 6)
+        return start_date.toLocaleDateString(this.$root.languageCode) + " - " + end_date.toLocaleDateString(this.$root.languageCode) + ", " + this.$root.django.gettext('CW') + " " + item.week
       },
       personalNoteString(personalNote) {
           let personalNoteString = "";