`codal.json` `target.dev` property looks like a boolean but it isn't

[microbit-carlos]

The CMakeLists.txt file just check if it has any value, so if the user sets "dev": false in the json file, it will still treat it as a dev build.

microbit-v2-samples/CMakeLists.txt

Lines 67 to 73 in ce0d2aa

	if("${codal.target.dev}" STRGREATER "")
	file(READ "./${LIB_DEST}/${codal.target.name}/target.json" device_json)
	message("${BoldMagenta}Using target.json (dev version) ${ColourReset}")
	else()
	file(READ "./${LIB_DEST}/${codal.target.name}/target-locked.json" device_json)
	message("${BoldMagenta}Using target-locked.json${ColourReset}")
	endif()

As the codal.json file in this repository contains "dev": true it's a fair expectation that changing it to false should disable it.

A fix in this repo should also be pushed upstream to lancaster-university/codal and to codal bootstrap (if applicable).