Update gradle.yml

Author: chrstphlbr

.github/workflows/gradle.yml

@@ -17,7 +17,7 @@ jobs:
   build:
     strategy:
       matrix:
-        os: [ubuntu-latest] # , macos-latest, windows-latest
+        os: [ubuntu-latest, macos-latest] # , windows-latest
 
     runs-on: ${{ matrix.os }}