Squashing nits

Author: jpolchlo

pystac/extensions/raster.py

@@ -771,7 +771,7 @@ def __repr__(self) -> str:
 
 
 class ItemAssetsRasterExtension(RasterExtension[item_assets.AssetDefinition]):
-    asset_defn: item_assets.AssetDefinition
+    asset_definition: item_assets.AssetDefinition
     """A reference to the :class:`~pystac.extensions.item_assets.AssetDefinition`
     being extended."""
 
@@ -781,10 +781,12 @@ class ItemAssetsRasterExtension(RasterExtension[item_assets.AssetDefinition]):
 
     def __init__(self, item_asset: item_assets.AssetDefinition):
         self.properties = item_asset.properties
-        self.asset_defn = item_asset
+        self.asset_definition = item_asset
 
     def __repr__(self) -> str:
-        return "<ItemAssetsRasterExtension AssetDefinition={}>".format(self.asset_defn)
+        return "<ItemAssetsRasterExtension AssetDefinition={}>".format(
+            self.asset_definition
+        )
 
 
 class SummariesRasterExtension(SummariesExtension):