Bump version to 1.22

Set version back to 1.21a18

Let's do another alpha release to test with 1.21a17

Bump version number to 1.21a16

Downgrade version number to 1.21a15, it was never released

Fix typo in image name for lint job

Update Django version info in the README

Bump version number to 1.21a12

Bump version number to 1.21a11

Bump version number to 1.21a10