MT#61971 remove python3-flake8-polyfill dependency

python3-flake8-polyfill is no longer available in debian/trixie
and therefore, it's good to stop using on it now. There is
also no logic in the project that relies on it.

Change-Id: Ibf69eaa9599adafc023c13aa9cd329618d0bca62

debian/control

@@ -18,7 +18,6 @@ Build-Depends:
  python3-flake8-class-newline,
  python3-flake8-comprehensions,
  python3-flake8-docstrings,
- python3-flake8-polyfill,
  python3-flake8-quotes,
  python3-pep8-naming,
  python3-prettytable,