Add more linters

[bupd]

We need to have linters to maintain code quality - not just finding issues but also on long term maintenance

https://golangci-lint.run/docs/linters/configuration/#unused

there are more of these linters one is unused - which we need to add to the golangci-lint config file.

[PrasunaEnumarthy]

@bupd Hi, I’d like to work on this issue.
To keep the change small and safe, I’m planning to start by enabling the 'unused' linter in 'golangci.yaml', since it is already supported by golangci-lint.
I’ll open an initial PR with just that change, and then handle any violations reported by CI. If the cleanup is small, I can include it in the same PR; otherwise I’ll split it into follow-up PRs.
Please let me know if this approach sounds good.

[bupd]

Yes go ahead