fix broken import in svd_merge_lora script

remove missing import, and remove unused imports

networks/svd_merge_lora.py

@@ -1,4 +1,3 @@
-import math
 import argparse
 import os
 import time
@@ -6,8 +5,6 @@ import torch
 from safetensors.torch import load_file, save_file
 from tqdm import tqdm
 from library import sai_model_spec, train_util
-import library.model_util as model_util
-import lora
 
 
 CLAMP_QUANTILE = 0.99