CompatHelper: bump compat for JLD2 to 0.5, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the JLD2 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.

[JonasIsensee]

This should be just fine to merge.

If you want to make extra sure that users won't encounter errors, you can bump the lower compat bound to 0.5.
(Files created with JLD2 > v0.5.0 cannot be read by older JLD2 versions <0.5.0 but older versions will at least throw a warning to upgrade before erroring)