Container build fails if notebook filenames contain space

[dsavchenko]

E.g.

�[36mINFO�[0m[0158] RUN for nn in /repo/*.ipynb; do     /tmp/yq -i -p json -o json '.metadata.kernelspec.name |= "python3"' $nn; done 
�[36mINFO�[0m[0158] Cmd: /usr/local/bin/_dockerfile_shell.sh     
�[36mINFO�[0m[0158] Args: [for nn in /repo/*.ipynb; do     /tmp/yq -i -p json -o json '.metadata.kernelspec.name |= "python3"' $nn; done] 
�[36mINFO�[0m[0158] Util.Lookup returned: &{Uid:57439 Gid:57439 Username:mambauser Name: HomeDir:/home/mambauser} 
�[36mINFO�[0m[0158] Performing slow lookup of group ids for mambauser 
�[36mINFO�[0m[0158] Running: [/usr/local/bin/_dockerfile_shell.sh for nn in /repo/*.ipynb; do     /tmp/yq -i -p json -o json '.metadata.kernelspec.name |= "python3"' $nn; done] 
Error: stat /repo/Meerkat: no such file or directory
Error: stat /repo/Sources: no such file or directory
error building image: error building stage: failed to execute command: waiting for process to exit: exit status 1

Using e.g. find instead of loop may fix