tdesktopPackages.preview: 1.4.4 -> 1.4.7

TODO: We're still using the old API ID (like the Arch package) which
should be used for testing only.
I've tried to contact the Telegram team multiple times via different
channels but didn't get a response so far. See [0],[1] for more details.

[0]: https://github.com/telegramdesktop/tdesktop/issues/4717
[1]: https://github.com/telegramdesktop/tdesktop/commit/65b2db216033aa08b7bc846df27843e566f08981