Only assert if go package is present if generating go types

[MOmarMiraj]

As apart of !184 there has been a regression as if you build typeshare with all features and are typesharing not in Golang, the assert_go_package_is_present function will still be ran even though your generating for another language

Updated the code to only run the function if the language of the types being converted is Golang.

To test:
Download the latest typeshare-cli from main and try generating types for any language but Go without a --go-package in the cmd and a package in the typeshare.toml.Should error out with:

[2024-11-18 15:50:43.169602 -05:00] INFO [typeshare] cli/src/main.rs:49: typeshare started generating types
Error: Please provide a package name in the typeshare.toml or using --go-package <package name>

Try the same thing but install from my branch like so:

	cargo install --git https://github.com/MOmarMiraj/typeshare --branch omar/fix-go-package --features go

and should work as expected.

[darrell-roberts]

Requested change.