setup: prepare for pypi upload
also add build/ and dist/ to gitignore
related to swh-environment#1242 (closed)
Test Plan
https://test.pypi.org/project/swh-loader-mercurial/
Migrated from D497 (view on Phabricator)
also add build/ and dist/ to gitignore
related to swh-environment#1242 (closed)
https://test.pypi.org/project/swh-loader-mercurial/
Migrated from D497 (view on Phabricator)