Use vmtest 0.12.0

TODO: Should come from upstream.

Author: d-e-s-o

.github/workflows/test-linux.yml

@@ -58,7 +58,7 @@ jobs:
           EOF
           chmod a+x main.sh
       - name: Test
-        uses: danobi/vmtest-action@master
+        uses: d-e-s-o/vmtest-action@topic/0.12.0
         with:
           kernel: bzImage
           command: "/bin/bash -c ${{ github.workspace }}/main.sh"