Fix "generator didn't stop" update error for LPC55 devices

[daringer]

This PR fixes the:

Exception encountered: RuntimeError("generator didn't stop after throw()")

error by introducing a time.sleep(1) directly after asking the device to boot into the bootloader so that udev has enough time to properly handle the new device.

Checklist

Make sure to run make check and make fix before creating a PR, otherwise the CI will fail.

• [x] tested with Python3.11
• [x] signed commits

Test Environment and Execution

• OS: Arch
• device's model: NK3AN
• device's firmware version: 1.5

Fixes #394