devel/py-versioningit: Fix BUILD_DEPENDS and its usage

• Fix BUILD_DEPENDS: py-wheel is not needed
• Fix BUILD_DEPENDS usage: it should depend on the package, not the executable

from pyproject.toml:
[build-system]
requires = ["hatchling"]

Reference: https://github.com/jwodder/versioningit/blob/v3.3.0/pyproject.toml#L1-L2
Approved by: portmgr (blanket)
With hat: python