Update matrix.yml

Author: Ducasse

.github/workflows/matrix.yml

@@ -14,7 +14,7 @@ jobs:
   build:
     strategy:
       matrix:
-        os: [ macos-latest, ubuntu-latest ]
+        os: [ macos-latest, windows-latest, ubuntu-latest]
         smalltalk: [ Pharo64-8.0, Pharo64-7.0 ]
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.smalltalk }} on ${{ matrix.os }}