doi_classes: use 'apa-6th-edition' citation style instead of 'apa'

doi_classes.py

@@ -389,7 +389,7 @@ class Relation:
   @property
   def djson(self): return {'relatedIdentifier': self.value,'relatedIdentifierType':self.idtype,'relationType': self.rtype}
   @functools.cache
-  def get_citation(self,style='apa')->str:
+  def get_citation(self,style='apa-6th-edition')->str:
     #return 'Vigouroux, C., Bauer Aquino, C. A., Bauwens, M., Becker, C., Blumenstock, T., De Mazière, M., García, O., Grutter, M., Guarin, C., Hannigan, J., Hase, F., Jones, N., Kivi, R., Koshelev, D., Langerock, B., Lutsch, E., Makarova, M., Metzger, J.-M., Müller, J.-F., ? Toon, G. (2018). NDACC harmonized formaldehyde time series from 21 FTIR stations covering a wide range of column abundances. In Atmospheric Measurement Techniques (Vol. 11, Issue 9, pp. 5049?5073). Copernicus GmbH. https://doi.org/10.5194/amt-11-5049-2018\n'
     for doi_value in DOIRelationFactory.search_doi(self.value): #there should be only one hit
       response=requests.post(f'https://citation.doi.org/format?doi={self.value}&style={style}&lang=en-US')