Fix typo

Author: lossyrob

pystac/asset.py

@@ -84,7 +84,7 @@ def get_absolute_href(self) -> Optional[str]:
         href is relative).
 
         Returns:
-            str: The absolute HREF of this asset, or a relative HREF is an absolute HREF
+            str: The absolute HREF of this asset, or a relative HREF if an absolute HREF
             cannot be determined.
         """
         if not is_absolute_href(self.href):