CI: Add west blobs fetch instead of copy api directory

Since ArduinoCore-API has been made into a blob,
the CI procedure will be modified.

Signed-off-by: TOKITA Hiroshi <tokita.hiroshi@gmail.com>

Author: soburi

.github/workflows/build.yml

@@ -37,8 +37,7 @@ jobs:
 
       - name: Initialize
         run: |
-          git clone https://github.com/arduino/ArduinoCore-API.git $MODULE_PATH/../ArduinoCore-API
-          cp -rfp $MODULE_PATH/../ArduinoCore-API/api $MODULE_PATH/cores/arduino/
+          west blobs fetch arduinocore-zephyr
 
       - name: Setup Rust toolchain
         run: |