Test Python 3.13 on CI

It is currently a release candidate.

Author: EliahKagan

.github/workflows/pythonpackage.yml

@@ -14,12 +14,14 @@ jobs:
       fail-fast: false
       matrix:
         os: ["ubuntu-latest", "macos-latest", "windows-latest"]
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
         exclude:
         - os: "macos-latest"
           python-version: "3.7"
         include:
         - experimental: false
+        - python-version: "3.13"
+          experimental: true
 
     runs-on: ${{ matrix.os }}