deps.qt: Update Qt 6.6.3 download links to fix nightly builds

[PatTheMav]

Description

Update download links for Qt 6.6.3 to unbreak scheduled nightly builds.

Motivation and Context

Qt 6.6 is considered a historical version of Qt 6 and has thus been archived and is not available from the official releases directory anymore.

How Has This Been Tested?

Requires test run on CI.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[RytoEX]

Looks good to me. The archive URL also seems to have current releases. I guess they wanted official_releases to only contain currently supported releases, so we probably don't have to change this back at any time, unless they change their folder structure again.