refactor(tvix/eval): remove useless map call

Change-Id: Ifb59ef148ea4fab613f2e4efb133c04baafa3a98
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8141
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

tvix/eval/src/value/attrs.rs

@@ -103,11 +103,7 @@ where
     where
         T: IntoIterator<Item = (K, V)>,
     {
-        NixAttrs(AttrsRep::Im(
-            iter.into_iter()
-                .map(|(k, v)| (k.into(), v.into()))
-                .collect(),
-        ))
+        NixAttrs(AttrsRep::Im(iter.into_iter().collect()))
     }
 }