python-jsonpath-ng: drop ply, six and decorator dependencies

python-jsonpath-ng: drop ply, six and decorator dependencies

jsonpath-ng 1.8.0 vendors ply as jsonpath_ng._ply and no longer imports
six or decorator, so none are required at runtime.

It builds through the setuptools.build_meta legacy backend but never
declared setuptools as a build dependency; it was only present in the host
build env transitively via those packages' builds. Add python-setuptools/host
explicitly so the build no longer relies on that side effect.

The jsonpath_ng CLI takes a required expression argument and has no version
flag, so the generic version check cannot detect the package version from it.
Add a test-version.sh override and assert __version__ in test.sh instead,
mirroring python-jmespath.

Signed-off-by: Alexandru Ardelean <redacted>