Update python-publish.yml

Author: muyr

.github/workflows/python-publish.yml

@@ -19,7 +19,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v4
       with:
-        python-version: '3.x'
+        python-version: '3.7'
     - name: Install dependencies
       run: |
         python -m pip install -U pip poetry mkdocs mkdocs-material