Uses/go.mk: Remove ca_root_nss from FETCH_DEPENDS

Once upon a time (i.e. last I looked at it), Go knew how to look at
the cert.pem installed by ca_root_nss, and that's it. Over the last
couple years, Go learned how to look at the system CA store, making
ca_root_nss completely unnecessary.

Assuming that our cert store is equivalent to NSS's cert.pem, there
should be no functional change here. If you install ca_root_nss, Go
will use it.

All we're changing here is that Go used to have a FETCH_DEPENDS on
ca_root_nss for fetching package files and such, but now we're just
relying on the system CA store. This has no effect on the built
product in any way.

PR: 285611
Reviewed by: michaelo