Adding windows-2022 C++20

Author: rwgk

.github/workflows/ci.yml

@@ -49,9 +49,12 @@ jobs:
             python: '3.6'
             args: >
               -DPYBIND11_FINDPYTHON=ON
-          # Inject a couple Windows 2019 runs
           - runs-on: windows-2019
             python: '3.9'
+          - runs-on: windows-2022
+            python: '3.9'
+            args: >
+              -DCMAKE_CXX_STANDARD=20
 
     name: "🐍 ${{ matrix.python }} • ${{ matrix.runs-on }} • x64 ${{ matrix.args }}"
     runs-on: ${{ matrix.runs-on }}