Fix CI: Add wordcloud and nltk to test dependencies

CI was failing with:
  ModuleNotFoundError: No module named 'wordcloud'

Added wordcloud and nltk to pip install command in tests.yml
to match requirements-dev.txt dependencies.

This fixes visualization test imports that depend on
word_clouds.py which requires the wordcloud library.

Related to #33

Author: jeremymanning

.github/workflows/tests.yml

@@ -39,7 +39,7 @@ jobs:
         python -m pip install --upgrade pip
         pip install pytest pytest-cov
         pip install "numpy<2" scipy transformers matplotlib seaborn pandas tqdm
-        pip install cleantext plotly scikit-learn
+        pip install cleantext plotly scikit-learn wordcloud nltk
         pip install torch --index-url https://download.pytorch.org/whl/cpu
         pip install -e .