Rename the branch `master` to `main` to match the TFX Addons pattern

[codesue]

Discussed in https://github.com/tensorflow/model-card-toolkit/discussions/236

^{Originally posted by **hanneshapke** October 26, 2022} Should we rename `master` to `main` to match the TFX Addons pattern? Why? https://www.theserverside.com/feature/Why-GitHub-renamed-its-master-branch-to-main

---

• [x] Post a discussion topic in the Announcements category to notify contributors about this change. Be sure to provide context on why the change is happening, the anticipated timeline for when the change will happen, and any action items for contributors. If you don't have the right permissions to do this yourself, tag @hanneshapke or @codesue so they can publish the post on your behalf.
• [x] Replace relevant mentions of "master" in the codebase with "main" and submit a pull request with your changes.
• [x] If you have permissions to update repo settings, merge your approved pull request and follow the instructions in GitHub's renaming a branch guide to rename "master" to "main". If you don't have the right permissions to do this yourself, tag @hanneshapke or @codesue so they can merge your branch and rename the default branch.

[sklin93]

@codesue Hi Sue, I don't seem to have permission to post on the announcement page. Could you please post an announcement? About the post content:

• Why the change is happening: https://www.theserverside.com/feature/Why-GitHub-renamed-its-master-branch-to-main (same link as mentioned by you above)
• Timeline: the code is ready, so it really depends on what is more convenient for contributors (since there's the holiday); what do you recommend? This week or the first week of Jan?
• Action items for contributors: follow the "What Your Teammates Have to Do" section on this page.

Thank you!

[codesue]

Thanks for picking this up, @sklin93! The discussion and issue have been up for a while now and there haven't been many active contributors in the past few months, so let's go with whenever is most convenient for you. Which timeline do you prefer?

[sklin93]

The first weekend of January (Jan 7-8) would be better! Thank you @codesue!

[sklin93]

@codesue hi Sue, I created the pull request. Could you review, approve and merge it when you have time? Thanks!