Simplify speedtest-cli installation steps

Updated installation instructions for speedtest-cli to use a single command.

src/content/blog/02-speedtest-cli-in-noble/index.md

@@ -10,10 +10,7 @@ Ookla에서 제공하는 스크립트는 os 버전을 감지하나 noble은 지
 1) `sudo apt-get install curl`  
 2) `curl -s https://packagecloud.io/install/repositories/ookla/speedtest-cli/script.deb.sh | sudo bash`  
 3) `/etc/apt/sources.list.d/ookla_speedtest-cli.list` 에서 noble을 jammy로 바꾸면 됨
-4) ```bash
+4) `sudo apt update && sudo apt install speedtest`
-   sudo apt update
-   sudo apt-get install speedtest
-   ```
 끝.
 
 ```text