fix(ci): change runner to 'ubuntu-latest' in publish workflow

was undefined before

Author: hf-kklein

.github/workflows/python-publish.yml

@@ -36,7 +36,7 @@ jobs:
 
   build-n-publish:
     name: Build and publish Python 🐍 distributions 📦 to PyPI and TestPyPI
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     # Specifying a GitHub environment, # Specifying a GitHub environment, which is strongly recommended by
     #PyPI: https://docs.pypi.org/trusted-publishers/adding-a-publisher/
     # you have to create an environment in your repository settings and add the environment name here