Test on all GitHub runner images

This is mostly for fun, I don’t expect things to work on Windows.

Author: mgeisler

.github/workflows/build.yml

@@ -28,8 +28,15 @@ jobs:
     strategy:
       matrix:
         os:
+          - windows-2022
+          - windows-2019
           - ubuntu-latest
+          - ubuntu-22.04
+          - ubuntu-20.04
           - macos-latest
+          - macos-13
+          - macos-12
+          - macos-11
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout