Adapt docker build flow to latest rust:bookwarm release containing rustup update to version 1.28.0

Author: dmitrylavrenov

docker/build.sh

@@ -37,6 +37,10 @@ mkdir -p \
   "${BUILD_VOLUMES_PATH}/rustup" \
   "${HOST_TARGET}"
 
+docker run \
+  "$BUILDER_CONTAINER_TAG" \
+  rustup toolchain install
+
 # Run the build in the docker environment.
 docker run \
   --rm \