If we're trying to build a Golang package and our version of the Go compiler is too old for the project's requirements, the `go-module` eclass should bail early with an appropriate error message.

Currently, `go mod tidy` fails silently in the case of incompatibility, resulting in the build failing with cryptic error messages related to missing dependencies, which could easily mislead people into looking for the issue in the package's source code itself (e.g. an incomplete go.sum), which isn't the case.

Fixing this should be as easy as adding `|| die` to the `go mod tidy` line in `_go-module_src_unpack_verify_gosum`.