fix platformio install sometime failing on GH

Author: nicolas-rabault

.github/workflows/build.yml

@@ -89,8 +89,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        project_folders:
-          [
+        project_folders: [
             examples/projects/l0,
             examples/projects/Arduino,
             examples/projects/NUCLEO-L432KC,
@@ -122,6 +121,7 @@ jobs:
           python -m pip install --upgrade pip
           pip install wheel
           pip install platformio
+        retry: 3
 
       - name: Run PlatformIO
         run: |