bindings: python: tests: fix duplicate test name

bindings: python: tests: fix duplicate test name

Previously, the `test_rising_edge_event` test was defined twice.

The second instance of the test actually tested the falling edge event
and was shadowing the first test which tested the rising edge event.

Now, the second instance is renamed to `test_falling_edge_event` to
reflect what it is testing and to avoid the naming conflict.

Signed-off-by: Vincent Fazio <vfazio@xes-inc.com>
Link: https://lore.kernel.org/r/20241114145116.2123714-16-vfazio@xes-inc.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>