Go's semantic import versioning requires v2+ modules to include the
major version in the module path. This enables using proper version
tags (v3.x.x) instead of pseudo-versions.
Updated module path: code.gitcaddy.com/server/v3
Enable [unparam](https://github.com/mvdan/unparam) linter.
Often I could not tell the intention why param is unused, so I put
`//nolint` for those cases like webhook request creation functions never
using `ctx`.
---------
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: delvh <dev.lh@web.de>
