upscaling with Real ESRGAN v3 produces a neon image

[ssube]

Using the Real ESRGAN v3 model exported by the conversion script, I am consistently getting neon green/yellow images with some ghosting, at any scale factor.

This may be a problem with the scale factor in the training step, although there is also special behavior for the v3 model in https://github.com/ssube/onnx-web/blob/main/api/onnx_web/chain/upscale_resrgan.py#L53

[ssube]

This was caused by using the RRDB net instead of the SRVGG net. The Real ESRGAN stage will need to have some more logic to switch between those, and I need to write an ONNX wrapper for the SRVGG class if possible (#113).