Fix build badge

Author: myrontuttle

project-template/README.md.jinja

@@ -1,6 +1,6 @@
 # {{project_name}}
 
-[![Build status](https://github.com/{{ author_username }}/{{ project_name }}/workflows/build/badge.svg?branch=master&event=push)](https://github.com/{{ author_username }}/{{ project_name }}/actions?query=workflow%3Abuild)
+[![Build status](https://github.com/{{ author_username }}/{{ project_name }}/workflows/build/badge.svg?branch=main&event=push)](https://github.com/{{ author_username }}/{{ project_name }}/actions?query=workflow%3Abuild)
 [![Dependencies Status](https://img.shields.io/badge/dependencies-up%20to%20date-brightgreen.svg)](https://github.com/{{ author_username }}/{{ project_name }}/pulls?utf8=%E2%9C%93&q=is%3Apr%20author%3Aapp%2Fdependabot)
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 [![Security: bandit](https://img.shields.io/badge/security-bandit-green.svg)](https://github.com/PyCQA/bandit)