refactor(phase): write the summary VCF with htslib instead of fprintf (#229) - #239

No file matched to [/home/runner/work/vcfdist/vcfdist/**/*requirements*.txt,/home/runner/work/vcfdist/vcfdist/**/*requirements*.in,/home/runner/work/vcfdist/vcfdist/**/*constraints*.txt,/home/runner/work/vcfdist/vcfdist/**/*constraints*.in,/home/runner/work/vcfdist/vcfdist/**/pyproject.toml,/home/runner/work/vcfdist/vcfdist/**/uv.lock,/home/runner/work/vcfdist/vcfdist/**/*.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.