use uv and pioarduino core

Updated Python version and added uv installation step in GitHub Actions workflow.

Author: Jason2866

.github/workflows/build-rpi.yml

@@ -66,24 +66,18 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v5
-
-      # - name: Cache PlatformIO
-      #   uses: actions/cache@v4
-      #   with:
-      #     key: ${{ runner.os }}-pio
-      #     path: |
-      #       ~/.cache/pip
-      #       ~/.platformio
-
       - name: Python
         uses: actions/setup-python@v6
         with:
-          python-version: "3.x"
-
-      - name: Install PIO
+          python-version: "3.13"
+      - name: Install uv
+        uses: astral-sh/setup-uv@v6
+        with:
+          version: "latest"
+          enable-cache: false
+      - name: Install platformio
         run: |
-          python -m pip install --upgrade pip
-          pip install --upgrade platformio
+          uv pip install --system -U https://github.com/pioarduino/platformio-core/archive/refs/tags/v6.1.18.zip
 
       - name: Build Examples
         run: |