remove unnecessary import of ice cream

as the title says, this get's rid of the ice cream import, which is not used here.
Relevant if I want to run in an environment where icecream is not installed.

visual_encoder.py

@@ -9,7 +9,6 @@ import numpy as np
 import torch
 import torch.nn as nn
 import torch.utils.checkpoint
-from icecream import ic
 
 def get_abs_pos(abs_pos, tgt_size):
     # abs_pos: L, C