Force codegen GO 1.16

Forced codegen via downgrading to Go 1.16:

```
$ env|grep GO

GOPATH=/Users/sebastian/go
```

```
$ go version

go version go1.16.10 darwin/amd64
```

```
$ echo $PATH

/Users/sebastian/.sdkman/candidates/micronaut/current/bin:/Users/sebastian/.sdkman/candidates/java/current/bin:/Users/sebastian/.cargo/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/TeX/texbin:/usr/local/MacGPG2/bin:/usr/local/share/dotnet:/Library/Frameworks/Mono.framework/Versions/Current/Commands:/bin:/Users/sebastian/go/bin
```

Signed-off-by: Sebastian J <[email protected]>