feat: changed backend-pg to backend

backend/src/db/instance.ts

@@ -0,0 +1,12 @@
+
+import knex from "knex"
+
+export type TDbClient = ReturnType<typeof initDbConnection>;
+export const initDbConnection = (dbConnectionUri: string) => {
+  const db = knex({
+    client: "pg",
+    connection: dbConnectionUri
+  });
+
+  return db;
+};