Start testing on 3.13 (prompt-toolkit#1949)

Author: Carreau

Diff for: .github/workflows/test.yaml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        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"]
 
     steps:
       - uses: actions/checkout@v4