CompatHelper: bump compat for "JLD2" to "0.3"

[github-actions[bot]]

This pull request changes the compat entry for the JLD2 package from 0.1, 0.2 to 0.1, 0.2, 0.3.

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.