feat: remove no longer needed db.close() in teardown

Author: vladholubiev

mongo-aggregate.test.js

@@ -11,7 +11,6 @@ describe('insert', () => {
 
   afterAll(async () => {
     await connection.close();
-    await db.close();
   });
 
   it('should aggregate docs from collection', async () => {

mongo-insert.test.js

@@ -11,7 +11,6 @@ describe('insert', () => {
 
   afterAll(async () => {
     await connection.close();
-    await db.close();
   });
 
   it('should insert a doc into collection', async () => {

readme.md

@@ -53,7 +53,6 @@ describe('insert', () => {
 
   afterAll(async () => {
     await connection.close();
-    await db.close();
   });
 });
 ```