Support golang purls with upper characters

[TG1999]

Golang purls treats purls with Upper characters differently.

https://go.dev/ref/mod#goproxy-protocol

Currently the code lives in https://github.com/aboutcode-org/go-inspector/blob/442bc5b83d5aeff2b7a27937ec82b63277bc8f7c/src/go_inspector/utils.py#L211

We are copyipng the code in this repo for now, but moving forward it needs to live in one repo only.