docs: replace codecov badge

Signed-off-by: Bo-Yi Wu <[email protected]>

Author: appleboy

README.md

@@ -2,6 +2,6 @@
 
 [![Run CI Lint](https://github.com/golang-queue/nats/actions/workflows/lint.yml/badge.svg)](https://github.com/golang-queue/nats/actions/workflows/lint.yml)
 [![Run Testing](https://github.com/golang-queue/nats/actions/workflows/testing.yml/badge.svg)](https://github.com/golang-queue/nats/actions/workflows/testing.yml)
-[![codecov](https://codecov.io/gh/golang-queue/nsq/branch/master/graph/badge.svg?token=V8A1WA0P5E)](https://codecov.io/gh/golang-queue/nsq)
+[![codecov](https://codecov.io/gh/golang-queue/nats/branch/main/graph/badge.svg?token=FFZN8E2ZZB)](https://codecov.io/gh/golang-queue/nats)
 
 NATS as backend with [Queue package](https://github.com/golang-queue/queue) (Connective Technology for Adaptive Edge & Distributed Systems)