update c demo

Author: ksyeo1010

.github/workflows/c-demos.yml

@@ -139,7 +139,7 @@ jobs:
 
     strategy:
       matrix:
-        device: [ cpu, cpu:1 ]
+        device: [ best ]
         machine: [ rpi3-32, rpi3-64, rpi4-32, rpi4-64, rpi5-64, pv-windows-arm64 ]
         include:
         - machine: rpi3-32