comms: run synapse admin ensure with python image

services/comms/oneoffs/synapse-admin-ensure-job.yaml

@@ -32,7 +32,7 @@ spec:
                     values: ["arm64"]
       containers:
         - name: ensure
-          image: registry.bstein.dev/infra/synapse-admin-ensure:0.1.0
+          image: python:3.12-slim
           imagePullPolicy: Always
           env:
             - name: VAULT_ADDR
@@ -46,6 +46,7 @@ spec:
             - -c
             - |
               set -euo pipefail
+              python -m pip install --no-cache-dir psycopg2-binary
               python - <<'PY'
               import json
               import os