Merge pull request #4 from adafruit/rp2040

whew pio support for rp2040!

Author: ladyada

.github/workflows/githubci.yml

@@ -20,7 +20,7 @@ jobs:
       run: bash ci/actions_install.sh
 
     - name: test platforms
-      run: python3 ci/build_platform.py zero
+      run: python3 ci/build_platform.py feather_m0_express metro_m4 pico_rp2040
 
     - name: clang
       run: python3 ci/run-clang-format.py -e "ci/*" -e "bin/*" -r .