Add CI tests using Python 3.14 (highest-supported)

Author: smheidrich

.github/workflows/test.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: ["3.8"]
+        python-version: ["3.8", "3.14"]
         os: [ubuntu-22.04, ubuntu-22.04-arm, windows-2022, macos-13]
         include:
           # set OS-specific cache paths