fix: correct syntax for openapi upload command in GitHub Actions workflow

Author: fcarrero

.github/workflows/rdme-openapi.yml

@@ -23,4 +23,4 @@ jobs:
       - name: Run `openapi` command 🚀
         uses: readmeio/rdme@v10
         with:
-          rdme: openapi upload--key=${{ secrets.README_API_KEY }} --branch=v2.3.0 --slug=conekta-api _build/api.yaml 
+          rdme: openapi upload --key=${{ secrets.README_API_KEY }} --branch=v2.3.0 --slug=conekta-api _build/api.yaml