Checkmk Werk 13369: License usage: Fix invalid period error if exactly one year is entered

ID: 13369 Title: License usage: Fix invalid period error if exactly one year is entered Component: Multisite Level: 1 Class: Bug fix Version: 2.1.0i1 If you entered exactly one year for the subscription period, e.g. 01.10.2021 - 30.09.2021, the error "Invalid subscription period. Must be at least one year" was shown.