fix(safe-outputs): add missing agent_last_committer field to test ExecutionContext structs

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jamesadevine

src/safeoutputs/create_pr.rs

@@ -2510,6 +2510,7 @@ new file mode 100755
             uploaded_pipeline_artifact_keys: std::sync::Arc::new(std::sync::Mutex::new(
                 std::collections::HashSet::new(),
             )),
+            agent_last_committer: None,
         };
         let outcome = result.execute_impl(&ctx).await.unwrap();
         assert!(!outcome.success);

src/safeoutputs/upload_build_attachment.rs

@@ -854,6 +854,7 @@ attachment-type: "agent-artifact"
             uploaded_pipeline_artifact_keys: std::sync::Arc::new(std::sync::Mutex::new(
                 std::collections::HashSet::new(),
             )),
+            agent_last_committer: None,
         }
     }