Bugfix release to fix a couple of issues.
Thanks to the effort of contributors for this new release @jlowin @nxtman123 @danpalmer @dan98765 @femesq 🎉

Changelog

• Don't overwrite fields on InputObject #752
• Incorrectly formatted error message #751
• Fix warning output #748

Docs and Internal

• Update contributing docs about using tox and sync tox pytest cmd with travis #744
• Add isort precommit hook & run on all files #743
• Add flake8 pre-commit hook and manually edit files to pass flake8 validation #746
• Add pyupgrade pre-commit hook and run on all files #736
• Update README Contributing section to encourage use of virtualenv #765
• Fix parameter order for Relay's Root-field #754
• Add python3.6 classifier to setup.py #763