Remove Windows 2019 from GHA matrix (EOL on GitHub's side)

Author: tianon

.github/workflows/ci.yml

@@ -19,7 +19,6 @@ jobs:
           - ubuntu-22.04
           - windows-2025
           - windows-2022
-          - windows-2019
     name: Build ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
     steps: