PB-2354 Fix link to point to existing release

Author: asteiner-swisstopo

app/stac_api/serializers/item.py

@@ -386,7 +386,7 @@ def get_stac_extensions(self, obj):
             extensions.append("https://stac-extensions.github.io/forecast/v0.2.0/schema.json")
         # Add CF extension when CF properties are present
         if obj.cf_standard_name is not None or obj.unit is not None:
-            extensions.append("https://stac-extensions.github.io/cf/v0.3.0/schema.json")
+            extensions.append("https://stac-extensions.github.io/cf/v0.2.0/schema.json")
         return extensions
 
     def get_stac_version(self, obj):