Update Levenshtein.ipynb

Fix a tiny typo in Levenshtein notebook.

src/dinglehopper/notebooks/Levenshtein.ipynb

@@ -22,7 +22,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "dinglehopper uses to have its own (very inefficient) Levenshtein edit distance implementation, but now uses RapidFuzz."
+    "dinglehopper used to have its own (very inefficient) Levenshtein edit distance implementation, but now uses RapidFuzz."
    ]
   },
   {