Avoid problems with Python dependencies

This would fix #33, #35, and parts of #19

Currently there's a Python dependency, which is only used as an example of being able to host a Python app in Aspire. It's not really essential to the flow of eShopSupport. But this is causing a lot of trouble because (1) you have to restore the `pip` dependencies manually; (2) this might or might not succeed, depending on your Python version and OS configuration; (3) even if it does, it will only work at runtime if you have CUDA-compatible hardware.

We should make this better. Options:

1. We can move the Python dependency into a Docker container. That will solve problems (1) and (2) above, though perhaps not (3).
2. We could make the Python dependency optional, defaulting to "not used". Then by default we simply wouldn't use the Python-based classifier and all newly-filed tickets would default to type "unknown". People who want to enable the Python classifier would be able to do so, but would then have to sort out making it run on their machine.
3. We could just remove the Python dependency entirely and do the classification via .NET.