CompatHelper: bump compat for ForwardDiff to 1, (keep existing compat)

This pull request changes the compat entry for the `ForwardDiff` package from `0.10` to `0.10, 1`. 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.