Tutorial: Fix exercise in Step 5 to match solution provided in Step 6

If you look at the solution for Step 6, you will see `0.0001` rather
than `0.00001` used for the last test case.  Fix the typo.

Help/guide/tutorial/Step5/CMakeLists.txt

@@ -61,4 +61,4 @@ target_include_directories(Tutorial PUBLIC
 # Hint: Use the PASS_REGULAR_EXPRESSION property with "4 is 2"
 
 # TODO 9: Add more tests. Create a function called do_test to avoid copy +
-# paste. Test the following values: 4, 9, 5, 7, 25, -25 and 0.00001.
+# paste. Test the following values: 4, 9, 5, 7, 25, -25 and 0.0001.