fix: avoid duplicate error message

"There was an error looking up a commit" could be printed twice in error stacks
due to a copy-paste error.

Author: Byron

gix-revision/src/graph/errors.rs

@@ -14,7 +14,7 @@ pub mod lookup {
         #[derive(Debug, thiserror::Error)]
         #[allow(missing_docs)]
         pub enum Error {
-            #[error("There was an error looking up a commit")]
+            #[error(transparent)]
             Find(#[from] crate::graph::lookup::Error),
             #[error(transparent)]
             ToOwned(#[from] crate::graph::commit::to_owned::Error),