Add Python 3.13 to test matrix (#50)

* Add Python 3.13 to test matrix
* Fix upper Python bound

Author: freddyheppell

.github/workflows/test.yml

@@ -14,8 +14,9 @@ jobs:
     runs-on: ubuntu-latest
 
     strategy:
+      fail-fast: false
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
       - uses: actions/checkout@v4