Bump aiosignal from 1.3.2 to 1.4.0

Bumps [aiosignal](https://github.com/aio-libs/aiosignal) from 1.3.2 to 1.4.0.
- [Release notes](https://github.com/aio-libs/aiosignal/releases)
- [Changelog](https://github.com/aio-libs/aiosignal/blob/master/CHANGES.rst)
- [Commits](aio-libs/aiosignal@v1.3.2...v1.4.0)

---
updated-dependencies:
- dependency-name: aiosignal
  dependency-version: 1.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]