Fix fetch-jdk invocation.

Author: fniephaus

.github/workflows/main.yml

@@ -125,7 +125,7 @@ jobs:
       env: ${{ matrix.env }}
       run: |
         mkdir jdk-dl
-        ${MX_PATH}/mx fetch-jdk --jdk-id ${JDK} --to jdk-dl --alias ${JAVA_HOME}
+        ${MX_PATH}/mx --java-home= fetch-jdk --jdk-id ${JDK} --to jdk-dl --alias ${JAVA_HOME}
     - name: Update dependency cache
       if: ${{ contains(matrix.env.GATE, 'debug') || contains(matrix.env.GATE, 'style') }}
       run: sudo apt update