Add istore as pre-commit hook

[Nabellaleen]

As suggested in https://github.com/pre-commit/mirrors-isort , I also added an automatic pre-computing of known third party by using https://github.com/asottile/seed-isort-config

[coveralls]

Coverage remained the same at 91.899% when pulling d8f657a on Nabellaleen:precommit-isort into 1033de5 on graphql-python:master.

[coveralls]

Coverage remained the same at 91.899% when pulling d8f657a on Nabellaleen:precommit-isort into 1033de5 on graphql-python:master.

[coveralls]

Coverage remained the same at 91.899% when pulling d8f657a on Nabellaleen:precommit-isort into 1033de5 on graphql-python:master.

[coveralls]

Coverage remained the same at 91.899% when pulling d8f657a on Nabellaleen:precommit-isort into 1033de5 on graphql-python:master.

[coveralls]

Coverage remained the same at 91.899% when pulling bf28813 on Nabellaleen:precommit-isort into 1033de5 on graphql-python:master.

[jnak]

Looks good. I tend to prefer absolute imports so this feels like a slight regression to me. But that does not really matter as long as we are consistent across the repo.