rename master to main/latest

[robkooper]

This wll go through and setup the code to allow us to rename master branch to main. This is to match our branch names with many of the other github repositories.

github.io == latest
github.com == main

Description

Motivation and Context

Review Time Estimate

• Immediately
• Within one week
• When possible

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• My name is in the list of CITATION.cff
• I have updated the CHANGELOG.md.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[robkooper]

once this is merged we can rename master to main

[infotroph]

This looks great, thanks.

I do find that with three branches (develop, main, latest) I get confused about the relationships between them a lot more than when considering any two of those, and it's unintuitive that the same branch is main in some places but latest in others. I vaguely remember this being needed because of something to do with how github.io handles default branches, right? Would it be worth documenting the reasons behind that somewhere in our docs?

[dlebauer]

once this is merged we can rename master to main

So should we rename now?