Problem in ResNet50 backbone of "Image segmentation" example #169
Description
I suspect that the following code line from the Image segmentation example
backbone = Metalhead.ResNet50(pretrain=true).layers[1:end-3]is not doing what is intended since ResNet50 from Metalhead (https://github.com/darsnack/Metalhead.jl/tree/darsnack/vision-refactor) returns a 2 item Chain (backbone and head), and the 1:end-3 indexing returns an empty Chain.
Funny enough, with the model return by methodmodel (basically a Conv((1,1), 3=>32)) the example still works and is able to produce some image segmentation (does it works like just a pixel color indexer?).
I'd say the expected code should be something Metalhead.ResNet50(pretrain=true).layers[1].layers and I would open a PR, but I'm not sure since, with that, the example fails later in the training loop.