Revert "change the matrix to macOS for testing"

This reverts commit b11aeb58a5100f34c7d56c7a41516532ae83566d.

.github/workflows/build-old.yml

@@ -11,7 +11,7 @@ jobs:
 
         strategy:
             matrix:
-                os: [macos-latest]
+                os: [macos-latest, ubuntu-latest, windows-latest]
 
         steps:
             - name: Check out Git repository