workflow: Fix ncsref update

Used wrong format for boards.

Signed-off-by: Jorgen Kvalvaag <jorgen.kvalvaag@nordicsemi.no>

Author: jorgenmk

.github/workflows/ncsref-update.yaml

@@ -23,7 +23,7 @@ jobs:
     with:
       artifact_fw_version: ${{ needs.build.outputs.version }}
       artifact_run_id: ${{ needs.build.outputs.run_id }}
-      devices: '["thingy91x"]'
+      devices: thingy91x
       test_all: true
   update-pr-state:
     needs: [build, test]