feat: fix randn found element of type float at pos 2

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Description

The values passed from gradio's components here are always of the float type, which results in the outcomes of self.seed_resize_from_h // 8 and self.seed_resize_from_w // 8 being float values that merely appear to be integers. This can cause issues at the following location:

https://github.com/AUTOMATIC1111/stable-diffusion-webui/blob/master/modules/rng.py#L61

TypeError: randn(): argument 'size' must be tuple of ints, but found element of type float at pos 2

https://github.com/AUTOMATIC1111/stable-diffusion-webui/blob/master/modules/rng.py#L142

TypeError: slice indices must be integers or None or have an __index__ method

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests