try to correct ci

.github/workflows/build.yml

@@ -63,7 +63,7 @@ jobs:
       run: git submodule update --init lib/FreeRTOS-Kernel lib/lwip lib/sct_neopixel
 
     - name: Checkout pico-sdk
-      if: ${{ matrix.family }} == 'rp2040'
+      if: matrix.family == 'rp2040'
       run: |
         git clone --depth 1 https://github.com/raspberrypi/pico-sdk ~/pico-sdk
         echo >> $GITHUB_ENV PICO_SDK_PATH=~/pico-sdk