add "pdm debug" task

pyproject.toml

@@ -79,6 +79,7 @@ dev = [
 app     = "python -m kleinanzeigen_bot"
 compile.cmd = "python -O -m PyInstaller pyinstaller.spec --clean"
 compile.env = {PYTHONHASHSEED = "1", SOURCE_DATE_EPOCH = "0"} # https://pyinstaller.org/en/stable/advanced-topics.html#creating-a-reproducible-build
+debug   = "python -m pdb -m kleinanzeigen_bot"
 format  = "autopep8 --recursive --in-place src tests --verbose"
 lint    = {shell = "pylint -v src tests && autopep8 -v --exit-code --recursive --diff src tests && mypy" }
 scan    = "bandit -c pyproject.toml -r src"