Publish prereleases

[datho7561]

Describe the bug

It seems like since we migrated off Jenkins that we're no longer publishing prereleases.

Expected Behavior

Nightly prereleases available to test latest unreleased changes.

Current Behavior

No prereleases available.

Steps to Reproduce

1. Install extension through VS Code
2. There should be a "switch to prerelease" button

Environment

• Windows
• Mac
• Linux
• other (please specify)