cmd/go: fix TestScript/mod_sumdb_golang to avoid assumptions about @v/list
I accidentally fetched an invalid version of rsc.io/quote from
proxy.golang.org, which the proxy then cached and now includes in
https://proxy.golang.org/rsc.io/quote/@v/list.
That causes 'go get rsc.io/quote` to resolve to a different version
depending on whether the proxy is used.
Adjust the test to fetch an explicit version instead, since the choice
of 'latest' is mostly irrelevant to the checksum database logic that
the test is intended to verify.
Updates #32805
Fixes #32900
Change-Id: I075b1f62e8c71545d0fb2dd4bd77ba525fc2a36d
Reviewed-on: https://go-review.googlesource.com/c/go/+/184719
Run-TryBot: Bryan C. Mills <bcmills@google.com> Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>