boot-qemu.py: Add '--ephemeral-initrd' - #136

No file matched to [/home/runner/work/boot-utils/boot-utils/**/*requirements*.txt,/home/runner/work/boot-utils/boot-utils/**/*requirements*.in,/home/runner/work/boot-utils/boot-utils/**/*constraints*.txt,/home/runner/work/boot-utils/boot-utils/**/*constraints*.in,/home/runner/work/boot-utils/boot-utils/**/pyproject.toml,/home/runner/work/boot-utils/boot-utils/**/uv.lock,/home/runner/work/boot-utils/boot-utils/**/*.py.lock]. The cache will never get invalidated. Make sure you have checked out the target repository and configured the cache-dependency-glob input correctly.