build(deps): update attrs requirement from ~=20.2 to ~=20.3
build(deps): update attrs requirement from ~=20.2 to ~=20.3

Updates the requirements on [attrs](https://github.com/python-attrs/attrs) to permit the latest version.
- [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/20.2.0...20.3.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
PolyJIT/benchbuild,PolyJIT/benchbuild,PolyJIT/benchbuild,PolyJIT/benchbuild