py39-portend @3.2.0: can't open file 'setup.py': [Errno 2] No such file or directory

[ryandesign (Ryan Carsten Schmidt)]

​https://build.macports.org/builders/ports-10.11_x86_64-builder/builds/233630/steps/install-port/logs/stdio

/opt/local/Library/Frameworks/Python.framework/Versions/3.9/bin/python3.9: can't open file '/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_python_py-portend/py39-portend/work/portend-3.2.0/setup.py': [Errno 2] No such file or directory
Command failed:  cd "/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_python_py-portend/py39-portend/work/portend-3.2.0" && /opt/local/Library/Frameworks/Python.framework/Versions/3.9/bin/python3.9 setup.py --no-user-cfg build -j4 
Exit code: 2

[jmroot (Joshua Root)]

In 751e1d976fc911de4e7cd25b9cfc2f17800a1101/macports-ports (master):

py-portend: use pep517

Also remove redundant code.

Fixes: #68066