gomod: update zoekt
Created by: keegancsmith
Includes:
- https://github.com/sourcegraph/zoekt/commit/a201741 docker: pin version of alpine for ctags build
- https://github.com/sourcegraph/zoekt/commit/934fdb5 binds the index server on all addresses to allow external access for services such as prometheus
- https://github.com/sourcegraph/zoekt/commit/a07da6d Merge remote-tracking branch 'gerrit/master'
- https://github.com/sourcegraph/zoekt/commit/1ba953d shards: ignore fsnotify.ErrEventOverflow
- https://github.com/sourcegraph/zoekt/commit/a0c8067 shards: consolidate events before calling scan