sync virtualboxes

[yurikoles]

• Update virtualbox.rb
• Update virtualbox@beta.rb
• Update virtualbox@6.rb

Important: Do not tick a checkbox if you haven’t performed its action. Honesty is indispensable for a smooth review process.

In the following questions <cask> is the token of the cask you're submitting.

After making any changes to a cask, existing or new, verify:

• The submission is for a stable version or documented exception.
• brew audit --cask --online <cask> is error-free.
• brew style --fix <cask> reports no offenses.

---

This is a remake of the #218906, which I screwed up by force-pushing.

[yurikoles]

The test virtualbox@beta (macos-15, arm) failed due to a network error, and I don't have the restart failed jobs superpower.

curl: (92) HTTP/2 stream 1 was not closed cleanly: PROTOCOL_ERROR (err 1)
Error: Download failed on Cask 'virtualbox@beta' with message: Download failed: https://www.virtualbox.org/download/testcase/VirtualBox-7.1.11-169531-macOSArm64.dmg
Error: Process completed with exit code 1.

[p-linnane]

Seems to be a network issue with the runner. Works fine for me locally.