Move from individual code owners to just pinging all collaborators

[dead-claudia]

Description

Motivation and Context

Most collaborators have commit access, and it'd make it a little easier (and more likely) for pull requests to get reviewed. Also, most collaborators have merge access as well.

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation change

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have updated docs/changelog.md

[dead-claudia]

Merging. I forgot to merge this a while ago.