Improve info provided by ska3_update_summary

[javierggt]

This PR includes a few changes to the scripts used to edit skare3 release PRs.

Changes:

• modify ska3_update_summary to be able to handle ska3-core[-latest] and to include added/removed packages.
• parse conda package deps using space between package name and version. When running conda search --json with older conda versions, the separator between package and version was '==', now it is a space.
• add author information to the list of changes between releases
• when querying the issues related to a milestone, sort them by issue ID.

[taldcroft]

Can you add in the description what is driving this change? It looks fine but I'm curious and good to have something for the record.

[javierggt]

Sorry, I added a few little commits, so now this PR is bigger.

[taldcroft]

I'm assuming you are basically going in single-developer mode on this package and not planning to review. Let me know otherwise but I want to make sure you are not waiting on review.