Gatekeeper: Update kubectl image

Package Merge Request

Package Changes

https://repo1.dso.mil/platform-one/big-bang/apps/core/policy/-/blob/3.9.0-bb.2/CHANGELOG.md

Package MR

https://repo1.dso.mil/platform-one/big-bang/apps/core/policy/-/merge_requests/146

For Issue

Closes https://repo1.dso.mil/platform-one/big-bang/apps/core/policy/-/issues/170