Test across Windows, macOS and Linux in addition to the JDK matrix

Author: eskopp

.github/workflows/test.yml

@@ -7,10 +7,15 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+
+    defaults:
+      run:
+        shell: bash
 
     strategy:
       matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
         java: [8, 11, 17, 21, 25]
 
     steps: