cmd/go/internal/modfetch: update TestCodeRepo for gopkg.in/yaml.v2
cmd/go/internal/modfetch: update TestCodeRepo for gopkg.in/yaml.v2

The new yaml.v2 release broke the longtest builder. Update the expected
data.

Updates #28856

Change-Id: I98ec9e32e55bdb6b26b67e46dc16f34f77c2d40f
Reviewed-on: https://go-review.googlesource.com/c/go/+/198117
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>

CAFxX/go,nawawi/go,CAFxX/go,cloudflare/go,golang/go,golang/go,CAFxX/go,nawawi/go,CAFxX/go,golang/go,cloudflare/go,CAFxX/go,golang/go,cloudflare/go,golang/go,akutz/go,CAFxX/go,akutz/go,golang/go,nawawi/go,golang/go,golang/go,akutz/go,nawawi/go,cloudflare/go,nawawi/go,akutz/go,nawawi/go,CAFxX/go,cloudflare/go,nawawi/go,akutz/go,nawawi/go,cloudflare/go,akutz/go,akutz/go,cloudflare/go,akutz/go,cloudflare/go,CAFxX/go