Fix PyPy version requirement in README (3.11+, not 3.9+)

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: vthorsteinsson

README.md

@@ -147,7 +147,7 @@ and each token annotated with its lemma and POS tag (`no`=noun, `so`=verb):
 
 ## Prerequisites
 
-This package runs on CPython 3.9 or newer, and on PyPy 3.9 or newer.
+This package runs on CPython 3.9 or newer, and on PyPy 3.11 or newer.
 
 To find out which version of Python you have, enter: