Fix bug in Textual Inversion Unloading

[bonlime]

What does this PR do?

Fixes Textual inversion unloading bug. To reproduce:

import torch
from diffusers import AutoPipelineForText2Image

pipeline = AutoPipelineForText2Image.from_pretrained("stabilityai/stable-diffusion-xl-base-1.0")

print(pipeline.text_encoder.text_model.embeddings.token_embedding)
pipeline.load_textual_inversion("sd-concepts-library/gta5-artwork")
pipeline.unload_textual_inversion()
pipeline.load_textual_inversion("sd-concepts-library/gta5-artwork")
pipeline.unload_textual_inversion()
print(pipeline.text_encoder.text_model.embeddings.token_embedding)

Would print:

Embedding(49408, 768)
Embedding(49409, 768) <- note 49409 instead of 49408 here

Due to incorrect tokenizer size, after adding embedding 2nd time, it's not being correctly reset. After this PR the output would be correct:

Embedding(49408, 768)
Embedding(49408, 768)

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[bonlime]

hi @sayakpaul can you please chech the PR? it's really tiny

[sayakpaul]

Thanks! Could you also add / update tests for this?

[github-actions]

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[sayakpaul]

@bonlime a gentle ping here.

[HuggingFaceDocBuilderDev]

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[bonlime]

@sayakpaul gentle ping worked :)

[sayakpaul]

@yiyixuxu could you give this a look?.

[sayakpaul]

Just a single comment.

[yiyixuxu]

thanks!

[yiyixuxu]

can you make style?

[bonlime]

Fixed style

[yiyixuxu]

thanks for the PR!