Remove buf breaking exception (#609)

<!-- Describe what has changed in this PR -->
**What changed?**
remove exception for "workflowservice/v1/request_response.proto"

<!-- Tell your future self why have you made these changes -->
**Why?**

This file is important, I don't want to hide it from this check for a
long time.

Author: ychebotarev

buf.yaml

@@ -13,8 +13,6 @@ breaking:
     - WIRE_JSON
   ignore:
     - google
-    # TODO (yuri) remove this. Added for "heartbeat" change (add
-    - temporal/api/workflowservice/v1/request_response.proto
 lint:
   use:
     - DEFAULT