RPi 5 not working due to hardware changes

matrixkeypad_rpi_simpletest.py fails on the Raspberry Pi 5 with:

`RuntimeError: Cannot determine SOC peripheral base address`

This is because the library necessary for gpio pins has changed on RPi5. Finding a way to handle this on all platforms would be ideal.

Start by running matrixkeypad_rpi_simpletest.py on a Raspberry Pi 5 and compare the failure with other supported platforms. Trace the GPIO initialization that produces “Cannot determine SOC peripheral base address,” then verify that the example handles the Raspberry Pi 5 and existing platforms without regressing their behavior.

Written by the indexing model from the issue text.