virtio-vsock: new release 0.4.0

[Ablu]

We have the same vm-memory dependency as virtio-queue. So the previous release should have been a major.

Summary of the PR

Please summarize here why the changes in this PR are needed.

Requirements

Before submitting your PR, please make sure you addressed the following requirements:

• [x] All commits in this PR are signed (with git commit -s), and the commit message has max 60 characters for the summary and max 75 characters for each description line.
• na All added/changed functionality has a corresponding unit/integration test.
• [x] All added/changed public-facing functionality has entries in the "Upcoming Release" section of CHANGELOG.md (if no such section exists, please create one).
• na Any newly added unsafe code is properly documented.

[Ablu]

@epilys: Could you do the yank + publish of the new version? :innocent: