Make versions of actions used in deploy and pr-preview workflows consistent.

Author: lyulka

.github/workflows/deploy.yml

@@ -15,10 +15,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout main branch 
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Install Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           # actions/setup-python recommends that python-version be fixed so that workflow runs are more 
           # predictable.

.github/workflows/pr-preview.yml

@@ -29,6 +29,8 @@ jobs:
 
       - name: Install Python
         uses: actions/setup-python@v4
+        with:
+          python-version: "3.12.7"
 
       - name: Install mkdocs
         run: pip install mkdocs