Deprecations

`Flux.params(model)` is deprecated. Use `Flux.trainable(model)` instead.

https://github.com/JuliaTeachingCTU/Julia-for-Optimization-and-Learning-Scripts/blob/3f707be0055594da837bd10da9a21c00b10f6e56/lecture_11/01-intro.jl#L37

```
params(m[2])[2] .= [-1; 0; 1]
# ->
params(Flux.trainable(m)[:layers][2])[2] .= [-1; 0; 1]
```