Update PostgreSQL.md

Author: aeneasr

examples/PostgreSQL.md

@@ -1,7 +1,7 @@
 ```go
 var db *sql.DB
 var err error
-pool, err = dockertest.NewPool("")
+pool, err := dockertest.NewPool("")
 if err != nil {
     log.Fatalf("Could not connect to docker: %s", err)
 }
@@ -24,4 +24,4 @@ if err = pool.Retry(func() error {
 
 // When you're done, kill and remove the container
 err = pool.Purge(resource)
-```
+```