Update filename in example. (matplotlib#23466)

The old name was when the example was still "bachelor's degree by
gender".

Author: anntzer

examples/showcase/stock_prices.py

@@ -102,7 +102,7 @@ def convertdate(x):
 # Finally, save the figure as a PNG.
 # You can also save it as a PDF, JPEG, etc.
 # Just change the file extension in this call.
-# fig.savefig('percent-bachelors-degrees-women-usa.png', bbox_inches='tight')
+# fig.savefig('stock-prices.png', bbox_inches='tight')
 plt.show()
 
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