Rename `ITK` repository default branch from `master` to `main`

[thewtex]

Description

main is now the default branch for GitHub projects as opposed to master. Provide the expected default.

Impact analysis

This will provide the expected default branch name, and it will also cause disruption to existing clones and forks.

Versions

Target for ITK 6.

Additional Information

Todo:

• Update related repositories
  • Update remote module's default branches (in progress)
  • Update ITKSphinxExamples
  • Update ITKSoftwareGuide
  • Update ITK-Wasm
  • Update itk-viewer
  • Update InsightSoftwareConsortium/ITKClangFormatLinterAction
  • Update InsightSoftwareConsortium/ITKPythonPackage
• Community notices (Discourse, etc.): https://discourse.itk.org/t/itk-git-repository-primary-branch-name-transition-from-master-to-main/7569
• https://adamj.eu/tech/2022/10/27/git-how-to-alias-master-as-main/
• Dashboard Scripts ENH: Update default dashboard branch to main #5429
• Scripts in the repository master to main #5426
• Release scripts master to main #5426
• Dashboard systems
• Setup nightly sync of master backwards compatibility branch to main
• Add to documentation on how to update local clone configuration and GitHub forks master to main #5426 (SetupForDevelopment.sh does this)
• GitHub Repository Settings Rename master default branch to main

@hjmjohnson

[github-actions]

Thank you for contributing an issue! 🙏

Welcome to the ITK community! 🤗👋☀️

We are glad you are here and appreciate your contribution. Please keep in mind our community participation guidelines. 📜
Also, please check existing open issues and consider discussion on the ITK Discourse. 📖

This is an automatic message. Allow for time for the ITK community to be able to read the issue and comment on it.

[dzenanz]

Welcome to the ITK community Matt 😄

[jhlegarreta]

All remotes having a LICENSE badge will surely have the default branch name hard-coded, e.g.
https://github.com/InsightSoftwareConsortium/ITKIOTransformDCMTK/blob/master/LICENSE

https://github.com/InsightSoftwareConsortium/ITKIOTransformDCMTK/pull/14/files#diff-7b3ed02bc73dc06b7db906cf97aa91dec2b2eb21f2d92bc5caa761df5bbc168fR9

So after the default branch gets renamed to main these links will no longer work. Having an easy way to apply changes to all remotes with a single command for this kind of changes is becoming a must, otherwise maintaining them is very time-consuming.

[thewtex]

I have started to rename the remote repository branches to main in the process of #4748 . We can use the all-repos tool to update the README badges.

[jhlegarreta]

Have renamed the default branch in ITKSoftwareGuide.

[thewtex]

Some WIP in #5426

[thewtex]

@hjmjohnson since you will be at Project Week, are you still OK with going ahead with this on Monday?

[thewtex]

@seanm could your nightly dashboard scripts please be updated to follow main?

[seanm]

@seanm could your nightly dashboard scripts please be updated to follow main?

How should I do that? The word master does not appear in my scripts.

[seanm]

Ah, I see it's in itk_common.cmake ... I guess that file was updated by you guys?