German Date for March changes from Mär to Mrz in Start Sprint Caledar when changed

1. Click Start Sprint-Button -> End Date for March is suggested as dd/Mär/yy
2. Click Calendar Icon to change date -> End Date for March is changed to dd/Mrz/yy
3. Click Start-Button -> Sprint cannot be started, error message is shown that the date format is incorrect

The Sprint can indeed be started when the format is manually overwritten with Mär.