MPFlash: Failed flash in CI should return error

[Josverl]

GH Action continues even if there is an error:

Run mpflash flash --version v1.22.2
15:57:55 | ⚠️ Disabling interactive mode in CI
15:57:55 | ℹ️ Interactive mode disabled. Skipping ask for user input.
15:57:55 | ℹ️ Found v1.22.2 firmware stm32/PYBV11-v1.22.2.hex for PYBV11 on 
/dev/ttyACM0.
[15](https://github.com/Josverl/micropython-stubs/actions/runs/9633972246/job/26569048476#step:8:16):57:55 | ℹ️ Updating PYBV11 on /dev/ttyACM0 to 1.22.2
15:57:55 | ℹ️ Entering bootloader on PYBV11 on /dev/ttyACM0 using method: mpy
15:57:58 | ℹ️ Using dfu-util
15:57:58 | ❌ File /home/jos/Downloads/firmware/stm32/PYBV11-v1.22.2.hex is not 
a .dfu file
15:58:31 | ✅ Flashed 1.23.0 to PYBV11
15:58:31 | ❌ Failed to flash PYBV11 on /dev/ttyACM0
15:58:31 | ❌ No boards were flashed

Log

https://github.com/Josverl/micropython-stubs/actions/runs/9633972246/job/26569048476 https://github.com/Josverl/micropython-stubs/actions/runs/9633972246/job/26569048476#step:8:24

[Josverl]

fixed in 3c9425fc2005e59b1641875534969c18a10ae131