Update niworkflows/interfaces/registration.py

Co-Authored-By: Chris Markiewicz <[email protected]>

Author: tsalo

niworkflows/interfaces/registration.py

@@ -347,7 +347,7 @@ def _post_run_hook(self, runtime):
 
 
 class EstimateReferenceImageInputSpec(BaseInterfaceInputSpec):
-    in_file = InputMultiPath(File(exists=True),
+    in_file = InputMultiObject(File(exists=True),
                              mandatory=True,
                              desc=('4D EPI file. If multiple files '
                                    'are provided, they are assumed '