Add Postgres 18 to supported databases (#7402)

Author: nurul3101

content/200-orm/500-reference/375-supported-databases.mdx

@@ -34,6 +34,7 @@ An asterisk (\*) indicates that the version number is not relevant; either all v
 | PostgreSQL           | 15      |
 | PostgreSQL           | 16      |
 | PostgreSQL           | 17      |
+| PostgreSQL           | 18      |
 | SQLite               | \*      |
 
 Note that a fixed version of SQLite is shipped with every Prisma ORM release.