fix nvidia 3000 series usage

docs/guidance/preparation.md

@@ -6,7 +6,7 @@
 ```
 conda create -n simswap python=3.6
 conda activate simswap
-conda install pytorch==1.8.0 torchvision==0.9.0 torchaudio==0.8.0 cudatoolkit=10.2 -c pytorch
+conda install pytorch==1.8.0 torchvision==0.9.0 torchaudio==0.8.0 cudatoolkit=11.1 -c pytorch -c nvidia -c conda-forge
 (option): pip install --ignore-installed imageio
 pip install insightface==0.2.1 onnxruntime moviepy
 (option): pip install onnxruntime-gpu  (If you want to reduce the inference time)(It will be diffcult to install onnxruntime-gpu , the specify version of onnxruntime-gpu may depends on your machine and cuda version.)