We already delete unused Qt modules, but we weren't deleting their PyQt5 modules. ----- taken from Electron-Cash/Electron-Cash@e044c94677160b6e6bb1a981b22a4b85103de6cb
Build locale files
contrib/make_locale
Prepare python dependencies used by Electrum.
contrib/make_packages
Create source tarball.
contrib/make_tgz