fixing data_directory not actually changing download directory and enforced spacy and thinc version requirements

[Torchee]

Description:
The fix/update is two-fold:

1. Solving the problem with ConvoKit download.
2. Ensuring ConvoKit would work with numpy 2.0.0+

Solutions to each update:

1. Updated util.py so that convokit downloads data to the directory specified in config.yml instead of to "downloads" always.
2. Updated setup.py to enforce spacy>=3.8.2 and thinc>=8.3.0, <8.4.0. Pre Spacy 3.8.2 was not compatible with numpy 2.0.0+ due to thinc issues. Spacy 3.8.2 is compatible with numpy 2.0.0+ but currently requires thinc to be between these versions, so as a temporary solution we enforce these requirements. We will continue to keep an eye on spacy releases and update the requirements if there are new releases targeting this issue.
   For additional insight into the issue:
   Numpy v2.0.0 breaks the ability to download models using spaCy explosion/spaCy#13528
   [BUG] -- numpy 2.0.0 raises ValueError in thinc.backends.numpy_ops explosion/thinc#939