Release 8.7.21

What's Changed

• CLDSRC-370: Release dev docker image by @dvasilas in #5153
• CLDSRV-374 putMetadata API route is not updating null version properly by @nicolas2bert in #5167
• CLDSRV-395 bump to 8.7.21 by @nicolas2bert in #5177

Full Changelog: 8.7.20...8.7.21