Migrate from master to main for default git branch
#### 🗹 Requirements

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#### 🎯 Subject of the issue

Experienced behavior:
Currently the default git branch is called "master". This is an outdated term.

Expected behavior:
The default git branch should be renamed to something such as "main" or "default" to avoid references to master/slave terminology, which is outdated.

Github has published [documentation on migrating from master to different branch names](https://github.com/github/renaming#renaming-the-default-branch-from-master). The IETF (internet engineering task force) also provides [this repo](https://github.com/ietf/terminology) for info and links to further docs such as the [NISTIR8366] Guidance for NIST Staff on Using Inclusive Language in Documentary Standards, National Institute of Standards and Technology (NIST) Interagency or Internal Report 8366 (NISTIR 8366), April 2021, https://doi.org/10.6028/NIST.IR.8366 More info can also be found in this current [RFC draft](https://datatracker.ietf.org/doc/html/draft-knodel-terminology-10#section-3.1).

Example:
master branch and references to it in the README.

I'd be happy to help migrate to whatever other branch name you see as a better fit.

#### 🔧 Your Setup

n/a

#### ★ Screenshots (Optional)

n/a