feat: dead letter mechanism for non-retryable messages

.github/workflows/internal_tests.yaml

@@ -59,7 +59,7 @@ jobs:
 
     services:
       postgres:
-        image: postgres:18.1
+        image: postgres:16.11
         env:
           POSTGRES_PASSWORD: postgres
         ports:

.github/workflows/planner_integration.yaml

@@ -56,7 +56,7 @@ jobs:
 
     services:
       postgres:
-        image: postgres:18.1
+        image: postgres:16.11
         env:
           POSTGRES_PASSWORD: postgres
         ports:

CONTRIBUTING.md

@@ -107,7 +107,7 @@ POSTGRESQL_DB_CONNECT_STRING="postgres://postgres:password@localhost:5432/postgr
 It assumes you have access to a Postgres server running reachable at $POSTGRESQL_DB_CONNECT_STRING.
 You can use `docker` to run a Postgres server locally:
 ```shell
-docker run -d --rm --name postgres -e POSTGRES_PASSWORD=password -p 5432:5432 postgres:18.1
+docker run -d --rm --name postgres -e POSTGRES_PASSWORD=password -p 5432:5432 postgres:16.11
 ```
 
 Run `webhook-gateway` integration tests using: