Use ghcr.io/kbeckmann/pico-sdk-builder:ubuntu-24.04

Author: kbeckmann

.github/workflows/20_build.yml

@@ -74,7 +74,7 @@ jobs:
         docker run \
         --mount type=bind,source=$(pwd),target=/ci \
         --workdir=/ci \
-        ghcr.io/kbeckmann/pico-sdk-builder:latest \
+        ghcr.io/kbeckmann/pico-sdk-builder:ubuntu-24.04 \
         bash -c "\
           git config --global --add safe.directory /ci/picocart64                    && \
           mkdir picocart64/sw/build                                                  && \