In case you missed it: We updated the .NET Core SDK on all release branches to .NET Core 3.1: https://github.com/apache/tinkerpop/pull/1261
So, if you want to build and test Gremlin.NET, you'll have to update your .NET Core SDK to version 3.1. This update apparently also caused the Docker build to fail. We're currently investigating this and will report back once it's fixed.
