[query] relax requirements of variant_qc

[danking]

CHANGELOG: hl.variant_qc no longer requires a locus field.

Fixes #12844.

[skr3178]

thank you for these changes.
I am facing trouble in installing this branch of the package.

i tried

pip install git+https://github.com/danking/hail.git@relax-variant-qc

git clone https://github.com/danking/hail.git --branch relax-variant-qc --single-branch
cd hail
pip install .