## Summary
Upgrade `google.golang.org/grpc/health/grpc_health_v1` which has a new
`List` method, so use the `UnimplementedHealthServer`.
## Related issues
- https://github.com/pomerium/ingress-controller/pull/1152
## User Explanation
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## Checklist
- [ ] reference any related issues
- [ ] updated unit tests
- [ ] add appropriate label (`enhancement`, `bug`, `breaking`,
`dependencies`, `ci`)
- [x] ready for review