Doesn't build all examples on the CI

[sdroege]

It should probably run something like cargo build --all-targets --all-features for the examples. All examples that require special features are currently not built, and the listbox_model example doesn't build currently without anybody noticing for that reason :)

[sdroege]

cargo build --all-targets --all-features

That also doesn't build all examples though... hrm!

[MarijnS95]

@sdroege Are the examples in a different crate? Might need to add --all/--workspace too so that it builds all examples (all-targets) for every crate :)