Extend RC testing period

Update the release schedule to extend the RC testing period to have enough time to run all the planned tests and still have some buffer to release a new RC in case of a major issue. With this new schedule, RC testing period will be two weeks.

This new release schedule does not affect the release date, which means that RC testing periods will overlap with different releases.

Signed-off-by: Walter Lozano walter.lozano@collabora.com