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
'github_enterprise': flask_oauth,
    'google': google,
    'google_auth': flask_oauth,
    'grpc': grpc,
    'hashicorp': hashicorp,
    'hdfs': hdfs,  
    'hive': hive,  
    'jdbc': jdbc,
    'jira': jira,
    'kerberos': kerberos,
    'kubernetes': kubernetes,   
    'ldap': ldap,
    "microsoft.azure": azure,
    "microsoft.mssql": mssql,
    "microsoft.winrm": winrm,
    'mongo': mongo,
    'mssql': mssql,  
    'mysql': mysql,
    'odbc': odbc,
    'oracle': oracle,
    'pagerduty': pagerduty,
    'papermill': papermill,
    'password': password,
    'pinot': pinot,  
    'plexus': plexus,
    'postgres': postgres,
    'presto': presto,
    'qds': qds,
    'rabbitmq': rabbitmq,
    'redis': redis,