FEAT: Check for v2+ major versions

[nieomylnieja]

Since neither go list nor GOPROXY protocol itself return a full list of available module versions which would also include v2+ versions, we need to manually check if v2+ versions exist for each package.

Once v2 is found, we should also check if v3 exists, and so on.

There might be a way to easily check that for public modules using deps.dev API,