Checklist:

• Create pull request for release notes based on the 3.6.4 milestone. PR: Release notes etc for 3.6.4 #5344
• Bump remaining unclosed issues.
• Update the translations from transifex.
• Ensure the pull request increments the version to 3.6.4 in restframework/__init__.py.
• Confirm with @tomchristie that release is finalized and ready to go.
• Ensure that release date is included in pull request.
• Merge the release pull request.
• Push the package to PyPI with ./setup.py publish.
• Tag the release, with git tag -a 3.6.4 -m 'version 3.6.4'; git push --tags.
• Deploy the documentation with mkdocs gh-deploy.
• Make a release announcement on the discussion group.
• Make a release announcement on twitter.
• Close the milestone on GitHub.