Try this

Author: Edouard-chin

dist/index.js

@@ -137982,8 +137982,8 @@ function dumpConfiguration(working_directory) {
   const artifact = new lib_artifact.DefaultArtifactClient()
   artifact.uploadArtifact(
     'rails_upgrade-config',
-    ['tmp/rails_upgrade-config.json'],
-    external_process_.cwd(),
+    ['rails_upgrade-config.json'],
+    `${external_process_.cwd()}/tmp`,
   )
 }
 

src/index.js

@@ -119,8 +119,8 @@ export function dumpConfiguration(working_directory) {
   const artifact = new DefaultArtifactClient()
   artifact.uploadArtifact(
     'rails_upgrade-config',
-    ['tmp/rails_upgrade-config.json'],
-    process.cwd(),
+    ['rails_upgrade-config.json'],
+    `${process.cwd()}/tmp`,
   )
 }