Fix devcontainer version.

Author: mbrt

.devcontainer/Dockerfile

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 ARG VARIANT=1.21
-FROM mcr.microsoft.com/vscode/devcontainers/go:0-${VARIANT}
+FROM mcr.microsoft.com/vscode/devcontainers/go:${VARIANT}-bookworm
 
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive && \
     apt-get -y install --no-install-recommends \