Remove references to old master branch

[axelson]

Description

Remove old outdated references to the previous master branch

A while back we switched the primary branch to main but we haven't yet removed all the references throughout the codebase

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• Improvement/refactoring (non-breaking change that doesn't add any feature
  but make things better)

Checklist

• Check other PRs and make sure that the changes are not done yet.