gatekeeper update to 3.15.0-bb.0

Package Merge Request

Package Changes

• Gluon 0.4.7 -> 0.4.8
• ironbank/opensource/openpolicyagent/gatekeeper v3.14.0 -> v3.15.0

Package MR

big-bang/product/packages/policy!203 (merged)

For Issue

Closes big-bang/product/packages/policy#204 (closed)

Upgrade Notices

N/A