BUG: fix pywt.pad for a zero pad width in 'smooth' and 'antisymmetric' (gh-589) - #854

cibuildwheel: Command ['/tmp/cibw-run-whcvi_rr/cp315-pyodide_wasm32/venv-test/bin/pip', 'install', 'pytest', 'matplotlib'] failed with code 1.