arm64 build of v0.13.0 can not work

[mloiseleur]

Describe the bug

Current arm64 docker image can not work. It contains:

1. An arm64 binary: /bin/athens-proxy
2. An amd64 binary: /bin/go

Error Message

When launching on an arm host, it says:

```console
INFO[2:02PM]: Exporter not specified. Traces won't be exported	
2024/01/03 14:02:37 error adding proxy routes: fork/exec /bin/go: exec format error
```

To Reproduce
Steps to reproduce the behavior:

docker run gomods/athens:v0.13.0

On an arm64 machine.

Expected behavior

docker image should be consistent on arch for all binary.