Fix PyPI publish workflow: use setup-python@v5 with Python 3.11

setup-python@v1 could not find Python 3.9 on current GitHub runners.
Bump checkout to v4 and pin an available Python version.

.github/workflows/publish-pypi.yml

@@ -7,11 +7,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@master
-    - name: Set up Python 3.9
-      uses: actions/setup-python@v1
+    - uses: actions/checkout@v4
+    - name: Set up Python
+      uses: actions/setup-python@v5
       with:
-        python-version: 3.9
+        python-version: '3.11'
 
     - name: Install pypa/build
       run: >-