fix: update unit tests and fix incorrect module path imports

[GeeDook]

The module path in go.mod must match the actual import path users need to use. Since our code is located in a subdirectory of the repository, the module path must include that subdirectory prefix.
https://go.dev/ref/mod#module-paths:~:text=Module%20paths%C2%B6,of%20a%20test.

Previously (incorrect): module 403unlocker-cli
Now (correct): module github.com/403unlocker/403unlocker-cli/subdir

This fixes the "invalid module path" error when running go mod commands.