Update action versions in python-publish.yml

Recent release action generated deprecated error: "Node.js 12 actions are deprecated. Please update the following actions to use Node.js 16: actions/checkout@v2, actions/setup-python@v2."

So simply increasing versions to match latest GitHub usage docs, hopefully works.

.github/workflows/python-publish.yml

@@ -13,9 +13,9 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: '3.x'
     - name: Install dependencies