Fix certificates workflows

Author: silvanocerza

.github/workflows/check-certificates.yml

@@ -28,12 +28,12 @@ jobs:
       - name: Set certificates path environment variable
         run: |
           # See: https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-commands-for-github-actions#setting-an-environment-variable
-          echo "FILES=\\\"$(ls -md ${{ github.workspace }}/certs/* | xargs | sed 's/, /","/g')\\\"" >> $GITHUB_ENV
+          echo "FILES=\"$(ls ${{ github.workspace }}/certs/* | xargs | sed 's/ /","/g')\"" >> $GITHUB_ENV
 
       - name: Get files list
         id: get-files
         run: |
-          JSON=$(echo "[${{ join(env.FILES) }}]" | jq -c '{"cert_file": .}')
+          JSON=$(echo '[${{ join(env.FILES) }}]' | jq -c '{"cert_file": .}')
           echo "::set-output name=certificates::$JSON"
 
   check-certificates: