Increased connection pool limits

closes https://linear.app/ghost/issue/AP-1069

- Increases connection pool limits. There were timeouts occuring due to
connection pool being exhausted.

Author: rmgpinto

src/db.ts

@@ -20,7 +20,7 @@ export const client = Knex({
           },
     pool: {
         min: 1,
-        max: 50,
+        max: 200,
     },
 });