Updating ECS, Jobs and Burst packages

So I've been using ECS version 11 for some time now and I've figured out there is new version. But in Package Manager even though it said "there are available updates" the dropdown for choosing a version was greyed out and the package was shown as "embedded". So I've removed the package and then entities package showed up in "all" and I've downloaded it. But I've had an error that "out variable is not part of C# 6". So I thought - maybe I also have to update burst and jobs. There was the same problem with embedded, but this time when I've removed the packages there was nothing about neither Jobs package nor Burst package in "all" to download. Does any know what I have to do to have those 3 packages update normally without all thouse shenanigans?