Fix calculation of DoW

The first week of a year (per ISO) is the first week containing a Thursday. %V calculates this.

Exchange two bits to fix this problem.

.github/workflows/meeting-reminder.yaml

@@ -19,7 +19,7 @@ jobs:
           echo "next_date=$next_date" >> "$GITHUB_OUTPUT"
           echo "next_date_iso=$next_date_iso" >> "$GITHUB_OUTPUT"
           echo "next_date_year=$next_date_year" >> "$GITHUB_OUTPUT"
-          next_date_week=$(date -d "next Wednesday" "+%U")
+          next_date_week=$(date -d "next Wednesday" "+%V")
           if [[ $(($next_date_week % 3)) != 0 ]];
           then
             echo "::notice::Wrong week, skip sending reminder."