chore: remove drone platform.

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

Author: appleboy

.drone.yml

@@ -2,7 +2,6 @@
 
 [![Run Tests](https://github.com/golang-queue/queue/actions/workflows/go.yml/badge.svg?branch=master)](https://github.com/golang-queue/queue/actions/workflows/go.yml)
 [![codecov](https://codecov.io/gh/golang-queue/queue/branch/master/graph/badge.svg?token=V8A1WA0P5E)](https://codecov.io/gh/golang-queue/queue)
-[![Build Status](https://cloud.drone.io/api/badges/golang-queue/queue/status.svg)](https://cloud.drone.io/golang-queue/queue)
 
 Queue is a Golang library for spawning and managing a Goroutine pool, Alloowing you to create multiple worker according to limit CPU number of machine.