chore: go mod updates

[astromechza]

It's been a while since we've updated the go dependencies here so I did the following:

1. update go toolchain
2. add replace pinning for mergo (following it's readme due to changed import path)
3. run go mod get -u ./... && go mod tidy
4. fixed a test

Dependabot isn't flagging any particular vuln, but there dependencies here been quite old.

[mathieu-benoit]

LGTM

Note/question: should we have Dependabot enabled in these repos to automate this process?

[astromechza]

LGTM

Note/question: should we have Dependabot enabled in these repos to automate this process?

We can. It's a relatively low risk repo - as it's just a CLI with no networking abilities.