chore(ci): add Python 3.13 to test matrix (#72)

Author: mharrisb1

.github/workflows/pr.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
     steps:
       - name: Checkout branch
         uses: actions/checkout@v3