cmd(server): fix build version embed

Created by: bobheadxi

Missed one in #11484 😞 The ldflags were changed in https://github.com/sourcegraph/sourcegraph/pull/10843

The current 3.17.0 single-container image has 0.0.0+dev as the version, but I think other deployment methods should be fine still

https://sourcegraph.com/search?q=repo:%5Egithub.com/sourcegraph/sourcegraph%24%40c667073852cfa57635ec8f45c8380edf8655cd76+-ldflags+%22-X+github.com/sourcegraph/sourcegraph/internal/version.version+AND+-ldflags+%22-X+github.com/sourcegraph/sourcegraph/internal/version.timestamp&patternType=literal

Sanity check:

VERSION=bob IMAGE=sourcegraph/server:bob cmd/server/build.sh
docker run --publish 7080:7080 --publish 127.0.0.1:3370:3370 --rm sourcegraph/server:bob