Prepare 1.3.0-rc.1 release candidate

[ml-evs]

To-do:

• Finalize changelog
• Finalize author list
• Update version number
• Run spell checker
• Release candidate v1.3.0-rc.1
• Validate machine-readable property definitions
• Feedback -- potential extra candidates
• Release v1.3.0
• Update optimade.org/specification

[ml-evs]

This is now ready for the rc.1 release -- will need two follow-up PRs to

a) reset the version number to ~develop again
b) prepare the 1.3 release proper (and remove -rc.1 from the changelog)

[merkys]

Just FYI, the release of v1.3 is still blocked by #563. Do we want to have rc.1 before #563 is fixed?

[ml-evs]

Just FYI, the release of v1.3 is still blocked by #563. Do we want to have rc.1 before #563 is fixed?

Ah right, I wasn't aware -- yes we should delay I think, though hopefully this can be done in the meeting tomorrow. If I get time today I'm going to add validation to the CI and see if I can't also do a reverse check for fields mentioned in the spec that do not have property definitions.

[ml-evs]

Just to summarise the last meeting, I'll wait until the end of the week before merging this in case @rartino has time to do the trajectory definitions. I've opened #577 which does some light-touch schema validation, but its not at the point where I can easily extract/find things that are undefined.

[ml-evs]

I think perhaps we should now merge this and #577 to get the release candidate out!

[merkys]

I think perhaps we should now merge this and #577 to get the release candidate out!

Agree. I have already started working on implementing v1.3 features in the COD. It would be nice to base them at least on a release candidate.