chore: fix the nested single quote

Author: samrose

.github/workflows/test.yml

@@ -26,7 +26,7 @@ jobs:
       - name: Set PostgreSQL versions
         id: set-versions
         run: |
-          VERSIONS=$(nix run nixpkgs#yq -- '.postgres_major[] ansible/vars.yml | nix run nixpkgs#jq -- -R -s -c 'split("\n")[:-1]')
+          VERSIONS=$(nix run nixpkgs#yq -- '.postgres_major[]' ansible/vars.yml | nix run nixpkgs#jq -- -R -s -c "split(\"\n\")[:-1]")
           echo "postgres_versions=$VERSIONS" >> $GITHUB_OUTPUT
   build:
     needs: prepare