Upgrade CI database versions (#36)

- PostgreSQL 11.5 to 18 (PostgreSQL 11 EOL)
- MySQL 5.7 to 9.7 (MySQL 5.7 EOL)

Author: fkmy

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
 
     services:
       postgres:
-        image: postgres:11.5
+        image: postgres:18
         ports: ["5432:5432"]
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
         env:
@@ -24,7 +24,7 @@ jobs:
           POSTGRES_PASSWORD: sequel_activerecord_connection
 
       mysql:
-        image: mysql:5.7
+        image: mysql:9.7
         ports: ["3306:3306"]
         options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=3
         env: