It's still called V1 so you get the update automatically.

Changes:

New ground texture that doesn't look like poo.
Lighting adjustments all over the map.
Changed mid massively, christmas tree is now the centre cap point.
Fixed various displacement texture seams
Training annotations now disappear after 8 seconds.
Removed giant gift particle from the sleigh so it no longer blocks vision.
More detailing to BLU's side.
More optimizing with prop fading.
Updated snowman models on both sides of the map to the latest version from their creator
Fixed snowmen being Spies (fixed having the red snowman on the blu side and the blu snowman on the red side)