fix: make default extent valid (#120)

Author: hrodmn

src/stactools/ephemeral/stac.py

@@ -25,7 +25,7 @@ def create_collection() -> Collection:
         Collection: STAC Collection object
     """
     extent = Extent(
-        SpatialExtent([[-180.0, 90.0, 180.0, -90.0]]),
+        SpatialExtent([[-180.0, -90.0, 180.0, 90.0]]),
         TemporalExtent([[datetime.now(tz=timezone.utc), None]]),
     )