Build error

## Build a firmware for Radio Master RP3-H

## Current Behavior

## Steps to Reproduce
> python C:\Users\markn\AppData\Roaming\ExpressLRS Configurator\firmwares\binary\ExpressLRS\src\python\binary_configurator.py --dir=C:\Users\markn\AppData\Roaming\ExpressLRS Configurator\firmwares\binary-targets --fdir=C:\Users\markn\AppData\Roaming\ExpressLRS Configurator\firmwares\cloud\ExpressLRS\a9d4a9cb5b5687c4c9d7e9e7fbdf44ad93651da6\firmware --target=radiomaster.rx_2400.rp3-h --phrase=*** --lbt --ssid=*** --password=*** --auto-wifi=60 --lock-on-first-connection --flash=dir --out=C:\Users\markn\AppData\Local\Temp\radiomaster.rx_2400.rp3-h.wifi_s7J7zM
Traceback (most recent call last):
File "C:\Users\markn\AppData\Roaming\ExpressLRS Configurator\firmwares\binary\ExpressLRS\src\python\binary_configurator.py", line 282, in

exit(main())
File "C:\Users\markn\AppData\Roaming\ExpressLRS Configurator\firmwares\binary\ExpressLRS\src\python\binary_configurator.py", line 220, in main
args = parser.parse_args()
File "argparse.py", line 1826, in parse_args
File "argparse.py", line 1859, in parse_known_args
File "argparse.py", line 2068, in _parse_known_args

File "argparse.py", line 2008, in consume_optional

File "argparse.py", line 1936, in take_action

File "C:\Users\markn\AppData\Roaming\ExpressLRS Configurator\firmwares\binary\ExpressLRS\src\python\binary_configurator.py", line 154, in __call__

raise argparse.ArgumentTypeError("readable_dir:{0} is not a valid path".format(prospective_dir))
argparse.ArgumentTypeError: readable_dir:C:\Users\markn\AppData\Roaming\ExpressLRS Configurator\firmwares\cloud\ExpressLRS\a9d4a9cb5b5687c4c9d7e9e7fbdf44ad93651da6\firmware is not a valid path

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## Possible Solution (Not obligatory)

## Context

## Your Environment

- Operating System and version: Windows 64
- TX hardware:TX 16mk3
- RX hardware: RM RPH-3

Start with src/python/binary_configurator.py around the argparse setup and the readable_dir validation at line 154, then reproduce the reported Windows command for target radiomaster.rx_2400.rp3-h. Done means the firmware build accepts the specified firmware directory and completes without the reported invalid-path error.

Written by the indexing model from the issue text.