Address issue regarding required affordances

[JKRhb]

@schulztr Hmm, unfortunately, the CI is still failing.

@JKRhb Sorry for the late response. If the Thing Models don't have the @Type-prefix tm: the Thing Model is handled as a Thing Description and an Error occurs. Otherwise the generate_coap.py-Script failes with the error message

line 181, in generate_coap_resources
    forms: List[dict] = affordance["forms"]
KeyError: 'forms'

If you print out the affordance name it appears that temperature_range is the affordance, which causes this error. This is why i thought that the missing form might be a problem but maybe we could just don't add an affordance to the resource list in line 182 if it don't have a form.

Thank you for pointing out these issues! I prefixed the Thing Model @type now :) Regarding the temperature_range issue: There is a mechanism in place in the generation script for determining required properties and leaving them out if they do not fulfill the requirements, but this is not working correctly. I will therefore remove the affordance for now and create an issue as a reminder that this needs to be addressed.

Originally posted by @JKRhb in #4 (comment)