Literally a typographical error

Author: AllenDowney

soln/chap18.ipynb

@@ -2644,9 +2644,9 @@
     "\n",
     "* \"How does `unittest` do test discovery?\"\n",
     "\n",
-    "\"Along with `assertEqual`, what are the most commonly used methods in `unittest.TestCase`?\"\n",
+    "* \"Along with `assertEqual`, what are the most commonly used methods in `unittest.TestCase`?\"\n",
     "\n",
-    "\"What are the pros and cons of `doctest` and `unittest`?\"\n",
+    "* \"What are the pros and cons of `doctest` and `unittest`?\"\n",
     "\n",
     "For the following exercises, consider asking an AI for help, but as always, remember to test the results."
    ]