fix: logic for datbase connection

Author: simllll

README.md

@@ -211,6 +211,8 @@ agenda.processEvery('3 days, 4 hours and 36 seconds');
 Specifies the database at the `url` specified. If no collection name is given,
 `agendaJobs` is used.
 
+By default `useNewUrlParser` and `useUnifiedTopology` is set to `true`,
+
 ```js
 agenda.database('localhost:27017/agenda-test', 'agendaJobs');
 ```

src/JobDbRepository.ts

@@ -208,10 +208,10 @@ export class JobDbRepository {
 			connectionString = `mongodb://${connectionString}`;
 		}
 
-		const client = await MongoClient.connect(url, {
-			...options,
+		const client = await MongoClient.connect(connectionString, {
 			useNewUrlParser: true,
-			useUnifiedTopology: true
+			useUnifiedTopology: true,
+			...options
 		});
 
 		return client.db();