fix mistake in env variable

src/main/resources/application.conf

@@ -10,7 +10,7 @@ myapp = {
       dbName            = ${?APP_DB_NAME}
       url               = "jdbc:postgresql://"${myapp.database.dbHost}":"${myapp.database.dbPort}"/"${myapp.database.dbName}
       user              = "test_user"
-      user              = ${?APP_DB_NAME}
+      user              = ${?APP_DB_USER}
       password          = "password"
       password          = ${?APP_DB_PASSWORD}
       numThreads        = 16