Bump attrs from 19.1.0 to 19.2.0
Bump attrs from 19.1.0 to 19.2.0

Bumps [attrs](https://github.com/python-attrs/attrs) from 19.1.0 to 19.2.0.
- [Release notes](https://github.com/python-attrs/attrs/releases)
- [Changelog](https://github.com/python-attrs/attrs/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/python-attrs/attrs/compare/19.1.0...19.2.0)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
aio-libs/aiohttp_session