Update CI workflow: switch npm package from libxmljs to libxslt

Author: AlirezaRa94

.github/workflows/ci.yml

@@ -53,7 +53,7 @@ jobs:
           fi
           rm -rf node_modules package-lock.json
           npm install enketo-transformer@4.1
-          npm install libxmljs
+          npm install libxslt
 
       - name: Run the transformer script
         shell: bash -l {0}