thanos update to 15.7.20-bb.1

Package Merge Request

Package Changes

https://repo1.dso.mil/big-bang/product/packages/thanos/-/blob/15.7.20-bb.1/CHANGELOG.md

Package MR

big-bang/product/packages/thanos!101 (merged)

For Issue

Closes big-bang/product/packages/thanos#77 (closed)

Upgrade Notices

N/A