chore(deps): bump github.com/zeromicro/go-zero in /rest/registry/etcd

Bumps [github.com/zeromicro/go-zero](https://github.com/zeromicro/go-zero) from 1.5.4 to 1.5.6.
- [Release notes](https://github.com/zeromicro/go-zero/releases)
- [Commits](zeromicro/go-zero@v1.5.4...v1.5.6)

---
updated-dependencies:
- dependency-name: github.com/zeromicro/go-zero
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

rest/registry/etcd/go.mod

@@ -2,4 +2,4 @@ module github.com/zeromicro/zero-contrib/rest/registry/etcd
 
 go 1.16
 
-require github.com/zeromicro/go-zero v1.5.4
+require github.com/zeromicro/go-zero v1.5.6