Remove julia example, since it does not build anymore #924

Job	Run time
Build jupyterlab (no kernels)	2m 31s
Build example-bash-minimal kernel	52s
Build example-c-minimal kernel	43s
Build example-elm-minimal kernel	59s
Build example-go-minimal kernel	40s
Build example-haskell-minimal kernel	1m 32s
Build example-javascript-minimal kernel	39s
Build example-nix-minimal kernel	56s
Build example-ocaml-minimal kernel	1m 4s
Build example-postgres-minimal kernel	45s
Build example-python-minimal kernel	42s
Build example-python-science kernel	51s
Build example-python-stable kernel	58s
Build example-r-minimal kernel	1m 38s
Build example-rust-minimal kernel	1m 38s
Build example-typescript-minimal kernel	45s
Build example-zsh-minimal kernel	41s
Build devshell	1m 7s
Test a template	50s
Build all kernels	3m 51s
Build docs	2m 9s
	25m 51s

Provide feedback