Task: Remove Nico as PR reviewer

[CodeWritingCow]

Describe the task

@zigouras has stepped back from this project, but GitHub Actions is still automatically assigning Nico as a reviewer for every pull request. Let's update GitHub Actions so it doesn't assign Nico as a reviewer anymore. (Also so he doesn't get spammed with notifications about having to review PRs.)

Acceptance Criteria

• When contributors submit a PR, GitHub doesn't automatically assign Nico as a reviewer

Additional context

• See issue DevOps: automate PR management tasks #791 and PR Lebovits/issu791 automate pr mgmt #795

[millmason]

@CodeWritingCow is there someone who should replace @zigouras as the backend reviewer, or should he just be removed from auto_assign.yml?

[CodeWritingCow]

@millmason let’s just remove Nico. I’m still automatically added as a reviewer on every PR. Also, we haven’t had many backend PRs recently so we’ll be okay for now.