use python matrix parameter

Author: Phil Varner

.github/workflows/pr.yml

@@ -21,13 +21,12 @@ jobs:
     strategy:
       matrix:
         python-version: ["3.12"]
-
     steps:
       - uses: actions/checkout@v4
       - run: pipx install poetry==1.7.1
       - uses: actions/setup-python@v5
         with:
-          python-version: "3.12"
+          python-version: ${{ matrix.python-version }}
           cache: poetry
       - name: Install dependencies
         run: poetry install --with=dev