Log message:
Mass-change BUILD_DEPENDS to TOOL_DEPENDS outside mk/.

Almost all uses, if not all of them, are wrong, according to the
semantics of BUILD_DEPENDS (packages built for target available for
use _by_ tools at build-time) and TOOL_DEPEPNDS (packages built for
host available for use _as_ tools at build-time).

No change to BUILD_DEPENDS as used correctly inside buildlink3.

As proposed on tech-pkg:
https://mail-index.netbsd.org/tech-pkg/2023/06/03/msg027632.html

Log message:
devel/py-pip-requirements-parser: import py-pip-requirements-parser-31.2.0

pip-requirements-parser is a mostly correct pip requirements parsing
library... because it uses pip's own code!

pip is the package installer for Python that is using "requirements"
text files listing the packages to install.