Sets release date for 4.0

Bumps version to 4.0.0rc6

Bumps version to 4.0.0rc5

Bumps version to 3.0.37

Bumps version to 3.0.36

Bumps version to 4.0.0rc3 (forgot to PGP sign, parity with celery 4 r…

…c number)

Bumps version to 4.0.0rc1

Bumps version to 3.0.35 and updates Changelog

Fixes build

Sets release-date for 3.0.33