gatekeeper update to 3.15.0-bb.3

Package Merge Request

Package Changes

https://repo1.dso.mil/big-bang/product/packages/policy/-/blob/3.15.0-bb.3/CHANGELOG.md

Package MR

big-bang/product/packages/policy!218 (merged)

For Issue

Closes (link to issue here)

Upgrade Notices

N/A