Add Python 3.13 setup step to test workflow (#1016)

Author: sbryngelson

.github/workflows/test.yml

@@ -48,6 +48,11 @@ jobs:
       - name: Clone
         uses: actions/checkout@v4
 
+      - name: Set up Python 3.13
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+
       - name: Setup MacOS
         if:   matrix.os == 'macos'
         run:  |