The **attrs** and **cattrs** packages version is incompatible.
Check command:
`pip check --use-feature=2020-resolver`

Code file: https://github.com/apache/airflow/blob/master/setup.py
Commit hash: 9150330
Line number:
694: 'attrs~=19.3'
696: 'cattrs~=1.0'

It will caused the final installed **attrs** version is higher than 20.1.0.

Why this happen?
From the dependency setting of **cattrs**:
https://github.com/Tinche/cattrs/blob/master/setup.py
Commit hash: 2f401b9
Line number:
12: "attrs >= 20.1.0"

setup.py
'pipdeptree',
    'pre-commit',
    'pylint==2.5.3',
    'pysftp',
    'pytest',
    'pytest-cov',
    'pytest-instafail',
    'pytest-rerunfailures',
    'pytest-timeouts',
    'pytest-xdist',
    'pywinrm',
    'qds-sdk>=1.9.6',
    'requests_mock',
    'semver',
    'setuptools',
    'testfixtures',
    'wheel',
    'yamllint',
]
if PY3:
    devel += ['mypy==0.770']
else:
    devel += ['unittest2']
devel_minreq = cgroups + devel + doc + kubernetes + mysql + password
devel_hadoop = devel_minreq + hdfs + hive + kerberos + presto + webhdfs
PROVIDERS_REQUIREMENTS: Dict[str, Iterable[str]] = {
    "amazon": amazon,
    "apache.cassandra": cassandra,
    "apache.druid": druid,
    "apache.hdfs": hdfs,