gomod: bump zoekt
Created by: keegancsmith
Includes the follow commits:
- https://github.com/sourcegraph/zoekt/commit/b94d682 gitindex: index symbolic links
- https://github.com/sourcegraph/zoekt/commit/2195b41 Replace Repo with RepoRegex implementation
- https://github.com/sourcegraph/zoekt/commit/4a99786 merging: count compound shards in loop
- https://github.com/sourcegraph/zoekt/commit/8a0872d queue: remove duplicative index_state_count prometheus metric
- https://github.com/sourcegraph/zoekt/commit/af2e605 merging: add metrics for shard count and janitor jobs
- https://github.com/sourcegraph/zoekt/commit/8a5ada5 all: resolve staticcheck issues