CompatHelper: add new compat entry for JLD2 in [weakdeps] at version 0.4, (keep existing compat)
This pull request sets the compat entry for the JLD2
package to 0.4
.
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. Note: Consider registering a new release of your package immediately after merging this PR, as downstream packages may depend on this for tests to pass.