chore: use setup-python action to upgrade pip

Signed-off-by: blam <ben@blam.sh>

.github/workflows/verify_microsite.yml

@@ -34,6 +34,9 @@ jobs:
         uses: actions/setup-node@60edb5dd545a775178f52524783378180af0d1f8 # v4.0.2
         with:
           node-version: 18.x
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.9'
 
         # Skip caching of microsite dependencies, it keeps the global cache size
         # smaller, which make Windows builds a lot faster for the rest of the project.
@@ -48,7 +51,7 @@ jobs:
         run: yarn build:api-docs
 
       - name: Install MkDocs dependencies
-        run: pip3 install mkdocs mkdocs-techdocs-core
+        run: pip install mkdocs mkdocs-techdocs-core
 
       - name: Build MkDocs for TechDocs
         run: mkdocs build --strict