update linux deb install flow

Author: IldySilva

cmd/migrate/README.md

@@ -27,10 +27,8 @@ $ scoop install migrate
 ### Linux (*.deb package)
 
 ```bash
-$ curl -L https://packagecloud.io/golang-migrate/migrate/gpgkey | apt-key add -
-$ echo "deb https://packagecloud.io/golang-migrate/migrate/ubuntu/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/migrate.list
-$ apt-get update
-$ apt-get install -y migrate
+$ curl -s https://packagecloud.io/install/repositories/golang-migrate/migrate/script.deb.sh | sudo bash
+$ sudo apt-get install migrate
 ```
 
 ### With Go toolchain