CompatHelper: bump compat for "LearnBase" to "0.5"

[github-actions[bot]]

This pull request changes the compat entry for the LearnBase package from ^0.4 to ^0.4, 0.5.

This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.

[racinmat]

Don't merge this, because https://github.com/JuliaML/MLDataPattern.jl/pull/50 is not completed and we have never ran it with [email protected].