Bump attrs from 19.3.0 to 20.3.0

Bumps [attrs](https://github.com/python-attrs/attrs) from 19.3.0 to 20.3.0.
- [Release notes](https://github.com/python-attrs/attrs/releases)
- [Changelog](https://github.com/python-attrs/attrs/blob/main/CHANGELOG.rst)
- [Commits](python-attrs/attrs@19.3.0...20.3.0)

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

test-requirements.txt

@@ -2,7 +2,7 @@ pytest==5.4.3 --hash=sha256:5c0db86b698e8f170ba4582a492248919255fcd4c79b1ee64ace
 mock==4.0.2 --hash=sha256:3f9b2c0196c60d21838f307f5825a7b86b678cedc58ab9e50a8988187b4d81e0
 importlib-metadata==1.6.1 --hash=sha256:15ec6c0fd909e893e3a08b3a7c76ecb149122fb14b7efe1199ddd4c7c57ea958
 more-itertools==8.3.0 --hash=sha256:7818f596b1e87be009031c7653d01acc46ed422e6656b394b0f765ce66ed4982
-attrs==19.3.0 --hash=sha256:08a96c641c3a74e44eb59afb61a24f2cb9f4d7188748e76ba4bb5edfa3cb7d1c
+attrs==20.3.0 --hash=sha256:31b2eced602aa8423c2aea9c76a724617ed67cf9513173fd3a4f03e3a929c7e6 --hash=sha256:832aa3cde19744e49938b91fea06d69ecb9e649c93ba974535d08ad92164f700
 py==1.8.1 --hash=sha256:c20fdd83a5dbc0af9efd622bee9a5564e278f6380fffcacc43ba6f43db2813b0
 packaging==20.4 --hash=sha256:998416ba6962ae7fbd6596850b80e17859a5753ba17c32284f67bfff33784181
 pluggy==0.13.1 --hash=sha256:966c145cd83c96502c3c3868f50408687b38434af77734af1e9ca461a4081d2d