Fix CI deploy

.github/workflows/ocaml.yml

@@ -121,7 +121,7 @@ jobs:
           git config user.email "${{ github.actor }}@users.noreply.github.com"
           git config user.name "${{ github.actor }}"
           git add ${{ needs.build-test-doc.outputs.ref }}
-          if [ -n "$(git diff --cached --quiet --exit-code)" ];
+          if [ "$(git diff --cached --quiet --exit-code)" ];
           then
             git commit -m "Deploy ${GITHUB_SHA}"
             git push -f "https://${{ github.actor }}:${{ github.token }}@github.com/${{ github.repository }}.git" gh-pages