CI: hack to shorten windows paths

 - win has a 32k char process arg limit
 - test classpath args for the junit JVM can go over this limit if
   the workspace path is too long and the process will fail to start
 - this moves the workspace close to the drive letter as workaround

.github/workflows/main.yml

@@ -2417,8 +2417,20 @@ jobs:
         exclude:
           - os: ${{ (contains(github.event.pull_request.labels.*.name, 'PHP') || contains(github.event.pull_request.labels.*.name, 'ci:all-tests') || github.event_name != 'pull_request') && 'nothing' || 'windows-latest' }}
       fail-fast: false
+    defaults:
+      run:
+        # hack: shorten paths to stay below 32k char process arg limit of windows
+        # note 'a' is apparently a mount point, we shouldn't go below that
+        # actions don't seem to care about the workspace attribute -> we symlink just for tests
+        working-directory: ${{ contains(matrix.os, 'windows') && 'D:\\a\\ws' || github.workspace }}
+
     steps:
 
+      - name: symlink short paths for windows
+        if: contains(matrix.os, 'windows') 
+        run: ln -s $(pwd) D:\\a\\ws
+        working-directory: ${{ github.workspace }}
+
       - name: Set up JDK ${{ matrix.java }} 
         uses: actions/setup-java@v4
         with: