python-jmespath: install jp as a non-byte-compiled command

python-jmespath: install jp as a non-byte-compiled command

Upstream ships its jp command-line tool as a plain "jp.py" script. Under
that name OpenWrt byte-compiles it into a non-executable /usr/bin/jp.pyc
(and the -src package keeps a "#!/usr/bin/env python" jp.py, which has no
interpreter on OpenWrt), so it fails the CI generic executable check.

Install it as /usr/bin/jp instead: the missing .py extension stops it from
being byte-compiled and Python3/FixShebang rewrites the shebang to
/usr/bin/python3. Add a test-version.sh override since jp takes a required
expression argument and has no version flag for the generic check to probe.

Signed-off-by: Alexandru Ardelean <redacted>