Pin python version in the release-dispatch workflow (#23660)

Author: alexeypilyugin

.github/workflows/release-dispatch.yml

@@ -44,6 +44,7 @@ env:
   # Default ddev version when callers don't pass `ddev-version`. Tracked by Renovate.
   # renovate: datasource=pypi depName=ddev
   DEFAULT_DDEV_VERSION: "16.0.0"
+  PYTHON_VERSION: "3.13"
 
 jobs:
   prepare:
@@ -59,6 +60,11 @@ jobs:
         with:
           fetch-depth: 0 # ddev needs full tag history
 
+      - name: Set up Python ${{ env.PYTHON_VERSION }}
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+
       - name: Install ddev
         run: pip install "ddev==${{ inputs.ddev-version || env.DEFAULT_DDEV_VERSION }}"