[tutorial] random inputs example does not allow floats

[anthonygego]

The run script fails in the user pass a float as input. int() actually does not allow any string which is not an integer.

demo-tasks/tutorial/07_random_inputs/run.py

Lines 10 to 11 in dd0b7fe

	student = int(get_input("student_code"))
	solution = int(math.sqrt(value/2))

This should be replaced by float() or rely on exception handling.