fix: Update to MorphoCloud/MorphoCloudWorkflow@343fe41

List of MorphoCloudWorkflow changes:

```
$ git shortlog 291c9bb..343fe41 --no-merges
Jean-Christophe Fillion-Robin (1):
      test
```

See MorphoCloud/MorphoCloudWorkflow@291c9bb...343fe41

.github/actions/extract-issue-fields/action.yml

@@ -49,7 +49,7 @@ runs:
       shell: bash
       run: |
         cat <<'EOF' | jq .
-        ${{ toJSON(steps.parse.outputs.data) }}
+        ${{ steps.parse.outputs.data }}
         EOF
 
     - name: Extract fields