Microservice example fails to build

[ktmitton]

Bug Report

Symptom

When trying to run the microservice example, the docker builds fail.

What is the expected behavior?

The docker-compose.yml file in the folder will build and start up containers for all four images.

What is the actual behavWhat did you see instead?ior?

The zipkin and rabbitmq images were pulled, but builds of webapi and workerservice would fail, stopping the process.

Reproduce

Starting at the root of the repo, run the following commands:

1. git checkout master
2. cd ./examples/MicroserviceExample/
3. docker-compose up --build

Additional Context

It looks like this started with #2599, if you pull the commit on #2591 then it works again. #2599 updated some of the dependencies to c# 10, and since the example gets built inside a netcore 3.1 container, there's a compatibility issue. I'll submit a PR to update the microservice example to net 6.0. Given the nature of the two projects, I'm hoping this won't be an issue, the actual target framework doesn't seem the focus of them.