Bugfix: modify return type of getIntV() and getExtV() to int32_t

[TDA-2030]

As shown in the following code, since the range of the data type uint16_t cannot express numbers greater than 78000, there is a comparison that is always true.

bool TMC4671::hasPower(){
	uint16_t intV = getIntV();
	return (intV > 10000) && (getExtV() > 10000) && (intV < 78000);
}

Therefore, the return type of getExtV() and getIntV() has been changed to int32_t

[Ultrawipf]

Thank you for finding this.
As the limit should be 65v it should usually not affect anything at the moment but it seems reasonable to change the type to 32b in case higher voltages are measured at some point.

Have to check if there is anything else that might be affected so i am going to merge into the dev branch first for the next release as it didn't seem to have caused issues yet.