pkg/debian: Also enforce XZ compression for meta package

.github/workflows/debian.yml

@@ -102,7 +102,7 @@ jobs:
       run: |
         cd pkg/debian/meta
         ./mkdebian.sh $(make -C ../kernel/linux -s kernelrelease) ${KERNEL_REVISION}
-        dpkg-buildpackage -b
+        dpkg-buildpackage -b -Zxz
 
     - name: Prepare release
       run: |