Missing values raise DecodingRequiredError

There are some VINs I've ran across where the make is not available after decoding, which would raise this exception. But even more prevalent is if you are decoding a gasoline car, electrification level will be None raising this:

vin/src/vin/__init__.py

Lines 261 to 263 in c79f282

    
           if self._electrification_level is None: 
        
               raise DecodingRequiredError() 
        
           return self._electrification_level

thanks!

	if self._electrification_level is None:
	raise DecodingRequiredError()
	return self._electrification_level