test/core_query.mk: Pin `farwest` in `core-query-deps-no-duplicates`
test/core_query.mk: Pin `farwest` in `core-query-deps-no-duplicates`

It was previously "pinned" to its `master` branch. Unforunately, the
testcase started to fail after `farwest` changed its own pinning of
`cowlib`.

By pinning to a specific version (or commit in this case) of `farwest`,
we make sure this won't happen again.

rabbitmq/erlang.mk,crownedgrouse/erlang.mk,ninenines/erlang.mk,jj1bdx/erlang.mk