[LOTP] Add go mod

# Description of the LOTP tool

`go mod` is a tool to download and verify dependencies for `go`. In a CI, since the dependencies didn't exist yet on the system, the verification is not done.

# Configuration files

```
go.mod
go.sum
```

# Documentation
https://go.dev/ref/mod#go-mod-file

## Additional notes

See GONOSUMDB for env-var.

Start with the go.mod and go.sum files named in the issue, then read the linked Go modules documentation and inspect how the CI currently handles dependencies. Done means the module configuration is present and CI can download and verify dependencies, including the noted GONOSUMDB consideration.

Written by the indexing model from the issue text.