Add opera-neon

[miccal]

After making all changes to the cask:

• brew cask audit --download {{cask_file}} is error-free.
• brew cask style --fix {{cask_file}} reports no offenses.
• The commit message includes the cask’s name and version.

Additionally, if adding a new cask:

• Named the cask according to the [token reference].
• brew cask install {{cask_file}} worked successfully.
• brew cask uninstall {{cask_file}} worked successfully.
• Checked there are no [open pull requests] for the same cask.
• Checked that the cask was not already refused in [closed issues].