Fix typo in main.py (introduced in #24)

[cpacker]

Running the demo scripts on a fresh clone of the repo throws an error:

(text2mesh) cpacker@...:text2mesh$ ./demo/run_alien_cobble.sh
Traceback (most recent call last):
  File "text2mesh/main.py", line 499, in <module>
    run_branched(args)
  File "text2mesh/main.py", line 34, in run_branched
    clip_model, preprocess = clip.load(args.clipmodel, device, jit=args.jit)
  File "anaconda3/envs/text2mesh/lib/python3.9/site-packages/clip/clip.py", line 124, in load
    raise RuntimeError(f"Model {name} not found; available models = {available_models()}")
RuntimeError: Model VIT-B/32 not found; available models = ['RN50', 'RN101', 'RN50x4', 'RN50x16', 'RN50x64', 'ViT-B/32', 'ViT-B/16', 'ViT-L/14', 'ViT-L/14@336px']

Seems like this is due to a typo here, VIT should be ViT.

Same command post-fix:

(text2mesh) cpacker@...:text2mesh$ ./demo/run_alien_cobble.sh
ModuleList(
  (0): FourierFeatureTransform()
  (1): ProgressiveEncoding()
  (2): Linear(in_features=515, out_features=256, bias=True)
  (3): ReLU()
  (4): Linear(in_features=256, out_features=256, bias=True)
  (5): ReLU()
  (6): Linear(in_features=256, out_features=256, bias=True)
  (7): ReLU()
  (8): Linear(in_features=256, out_features=256, bias=True)
  (9): ReLU()
  (10): Linear(in_features=256, out_features=256, bias=True)
  (11): ReLU()
)
ModuleList(
  (0): Linear(in_features=256, out_features=256, bias=True)
  (1): ReLU()
  (2): Linear(in_features=256, out_features=256, bias=True)
  (3): ReLU()
  (4): Linear(in_features=256, out_features=3, bias=True)
)
ModuleList(
  (0): Linear(in_features=256, out_features=256, bias=True)
  (1): ReLU()
  (2): Linear(in_features=256, out_features=256, bias=True)
  (3): ReLU()
  (4): Linear(in_features=256, out_features=1, bias=True)
)
  0%|                                                                                                                                           | 0/1500 [00:00<?, ?it/s]