Improve textual inversion compatibility

[suzukimain]

What does this PR do?

Fixes #10373

This PR fixes the issue of incompatibility in textual inversion between different SD versions such as SD 1.5 and SD 2.1

Example:

!pip install git+https://github.com/suzukimain/diffusers.git@textual_inversion

import torch
from diffusers import StableDiffusionPipeline
from huggingface_hub import hf_hub_download

pipe = StableDiffusionPipeline.from_pretrained("stabilityai/stable-diffusion-2-1", torch_dtype=torch.float16).to("cuda")

path = hf_hub_download(repo_id="gsdf/EasyNegative", filename="EasyNegative.safetensors", repo_type="dataset")

pipe.load_textual_inversion(path, token="EasyNegative")

Additionally, if you find any mistakes, please feel free to let me know.

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