chore(deps): update docker.io/postgres docker tag to v12.22

docker-compose.yml

@@ -19,7 +19,7 @@ services:
       - matrix
 
   db:
-    image: docker.io/postgres:12.22-alpine@sha256:eb37f58646a901dc7727cf448cae36daaefaba79de33b5058dab79aa4c04aefb
+    image: docker.io/postgres:12.22-alpine@sha256:9ba0467e7c907d0b32b647cd4e9af4b5f634ad964ce189c3815522aea3c97662
     restart: unless-stopped
     environment:
       - POSTGRES_USER=${DC_MATRIX_POSTGRES_USER:-synapse}