ci: GitHub Actions use windows latest

Author: henryborchers

.github/workflows/tox_matrix.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-2019]
+        os: [ubuntu-latest, macos-latest, windows-latest]
         python-version: ['3.10', '3.11', '3.12', '3.13']
         frontend: ["", "PySide6"]
       fail-fast: false