gatekeeper update to 3.15.0-bb.6

Package Merge Request

Package Changes

https://repo1.dso.mil/big-bang/product/packages/policy/-/blob/3.15.0-bb.6/CHANGELOG.md

Package MR

big-bang/product/packages/policy!206 (merged) big-bang/product/packages/policy!222 (merged)

For Issue

Closes big-bang/product/packages/policy#208 (closed)

Upgrade Notices

N/A