Update postgres Docker tag to v18.3

Author: renovate[bot]

.github/workflows/e2e_tests.yml

@@ -13,7 +13,7 @@ jobs:
 
     services:
       postgres:
-        image: postgres:18.2-alpine
+        image: postgres:18.3-alpine
         env:
           POSTGRES_USER: thesis-management-postgres
           POSTGRES_PASSWORD: thesis-management-postgres

docker-compose.prod.yml

@@ -105,7 +105,7 @@ services:
       - thesis-management-network
 
   db:
-    image: "postgres:18.2-alpine"
+    image: "postgres:18.3-alpine"
     container_name: thesis-management-db
     environment:
       - POSTGRES_USER=${SPRING_DATASOURCE_USERNAME}

docker-compose.yml

@@ -1,6 +1,6 @@
 services:
   db:
-    image: 'postgres:18.2-alpine'
+    image: 'postgres:18.3-alpine'
     container_name: thesis-management-db
     volumes:
       - ./db_backups:/db_backups