Fix time related bug in broadcast temporal test
Fix time related bug in broadcast temporal test

The old test assumes that a month has more than 28 days when building the expected result. This is not always true, in particular when the result includes february with 28 days.
To solve the problem the expected result is computed dynamically in the test.
roschaefer/rundfunk-mitbestimmen,roschaefer/rundfunk-mitbestimmen,roschaefer/rundfunk-mitbestimmen