Install instructions - add to project dependencies rather than direct install with pip

[elichad]

The install instructions in the README say to pip install flwrcrate on the command line. This should probably go in the project's pyproject.toml instead:

[project]
name = "quickstart-pytorch"
version = "1.0.0"
description = "Federated Learning with PyTorch and Flower (Quickstart Example)"
license = "Apache-2.0"
dependencies = [
    "flwr[simulation]>=1.24.0",
    "flwr-datasets[vision]>=0.5.0",
    "torch==2.8.0",
    "torchvision==0.23.0",
    "flwrcrate>=0.4.0"
]

This ensures it gets installed into the right environment, and if the user re-installs their project elsewhere, the dependency will be added in the new environment.