gatekeeper update to 3.20.0-bb.0

Package Merge Request

Package Changes

https://repo1.dso.mil/big-bang/product/packages/policy/-/blob/3.20.0-bb.0/CHANGELOG.md

Known Issues

Package changes going to pass-through and gluon updates have changed some pod names causing some package helm tests to fail if gatekeeper is enabled. This breakage occurs on master and does not appear related to these changes. issue big-bang/product/packages/policy#288 was written to address this.

Package MR

big-bang/product/packages/policy!323 (merged)

For Issue

Closes big-bang/product/packages/policy#286 (closed)

Upgrade Notices

N/A