Tax ID Code missing country

[samlown]

As reported here: invopop/gobl#448

When converting into CII, party tax codes must include the 2-letter country code as part of the tax ID.

[apardods]

Strange, it should already be doing that. The String() method here: https://github.com/invopop/gobl/blob/main/tax/identity.go#L93 already adds the country code, and the tests here: https://github.com/invopop/gobl.cii/blob/main/internal/gtoc/party_test.go#L45 checks for the tax ID with the country prefix. Maybe the country code prefix is not being correctly parsed and taken as empty somewhere, I'll look into it.

[MarlinKuhn]

It was just a problem in parsing not while creating the CII.

I Already fixed this in my PR.

2597709