Dump from Local Sqlite3 and Import in Heroku Production Server

I have Django App on Heroku.

My local dev server is running django with Sqlite, which contains lots of data(couple of gigs) that I want to transfer to Heroku Postgre.

Heroku provides this import/export guide that let's one export from local POSTGRE db, create a dumpfile and import it (pg:restore) on Prod. heroku DB.

How can I generate dump file from my Sqlite db and and import in Heroku Postgre ?