Bump safetensors to ~=0.4.0 (#4844)

## What type of PR is this? (check all applicable)

- [ ] Refactor
- [ ] Feature
- [ ] Bug Fix
- [x] Optimization
- [ ] Documentation Update
- [ ] Community Node Submission

## Description

@Millu pointed out this safetensors PR a few weeks ago, which claimed to
offer a performance benefit:
https://github.com/huggingface/safetensors/pull/362 . It was superseded
by https://github.com/huggingface/safetensors/pull/363 and included in
the latest [safetensors 0.4.0
release](https://github.com/huggingface/safetensors/releases/tag/v0.4.0).

Here are the results from my local performance comparison:
```
Before(0.3.1) / After(0.4.0)

sdxl:main:tokenizer from disk to cpu in                              0.46s / 0.46s
sdxl:main:text_encoder from disk to cpu in                           2.12s / 2.32s
embroidered_style_v1_sdxl.safetensors:sdxl:lora' from disk to cpu in 0.67s / 0.36s
VoxelXL_v1.safetensors:sdxl:lora' from disk to cpu in                1.64s / 0.60s
ryan_db_sdxl_epoch640.safetensors:sdxl:lora' from disk to cpu in     2.46s / 1.40s
sdxl:main:tokenizer_2 from disk to cpu in                            0.37s / 0.39s
sdxl:main:text_encoder_2 from disk to cpu in                         3.78s / 4.70s
sdxl:main:unet from disk to cpu in                                   4.66s / 3.08s
sdxl:main:scheduler from disk to cpu in                              0.34s / 0.33s
sdxl:main:vae from disk to cpu in                                    0.66s / 0.51s

TOTAL GRAPH EXECUTION TIME:                                        56.489s / 53.416s
```

The benefit was marginal on my system (maybe even within measurement
error), but I figured we might as well pull it.

pyproject.toml

@@ -72,7 +72,7 @@ dependencies = [
   "realesrgan",
   "requests~=2.28.2",
   "rich~=13.3",
-  "safetensors~=0.3.1",
+  "safetensors~=0.4.0",
   "scikit-image~=0.21.0",
   "semver~=3.0.1",
   "send2trash",