Building on Windows should remove all `__pycache__`

Feature or enhancement

The file Makefile.pre.in already has this target:

pycremoval:
	-find $(srcdir) -depth -name '__pycache__' -exec rm -rf {} ';'
	-find $(srcdir) -name '*.py[co]' -exec rm -f {} ';'

It would be useful to have an equivalent on Windows.

Pitch

This would be helpful when iterating on compiler/bytecode, instead of manually bumping the magic number at each build or manually removing all pycs. It's easy to forget and think there's a bug when in reality the .pyc files are just stale.

Inizia con il target pycremoval esistente in Makefile.pre.in e individua l’entry point della build Windows che fornisce una pulizia equivalente. Assicurati che il workflow Windows rimuova le directory pycache e i file *.py[co], quindi verifica che la pulizia possa essere utilizzata durante l’iterazione del compilatore o del bytecode.