refactor: refactor command execution for root user switch operation

- Change the name of the job from "switch root user" to "switch to root user"
- Replace the command "sudo su - -c 'whoami'" with "sudo whoami"

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

.github/workflows/ci.yml

@@ -269,7 +269,7 @@ jobs:
       - name: checkout
         uses: actions/checkout@v1
 
-      - name: switch root user
+      - name: switch to root user
         uses: ./
         with:
           host: ${{ secrets.HOST }}
@@ -281,4 +281,4 @@ jobs:
           command_timeout: 30s
           script: |
             whoami && echo 'hello world' && touch todo.txt
-            sudo su - -c 'whoami'
+            sudo whoami