Restore NLTK/TextBlob corpus downloads in tox commands_pre

The commands_pre section with punkt_tab and textblob corpus downloads
was accidentally dropped during the Poetry-to-uv migration. Without
these corpora, the summary evaluator tests fail with MissingCorpusError.

Author: jonathangreen

tox.ini

@@ -4,6 +4,10 @@ skipsdist = true
 
 [testenv]
 runner = uv-venv-runner
+commands_pre =
+    # TODO: This can be removed once NLTK merges https://github.com/sloria/TextBlob/pull/469
+    python -m nltk.downloader punkt_tab
+    python -m textblob.download_corpora
 commands =
     pytest {posargs:tests}
 passenv =