[AIRFLOW-4827] Remove compatible test for python 2

[zhongjiajie]

Make sure you have checked all steps below.

Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title. For example, "[AIRFLOW-XXX] My Airflow PR"
  • https://issues.apache.org/jira/browse/AIRFLOW-4827

Code Quality

• Passes flake8

[OmerJog]

Shouldnt you target https://issues.apache.org/jira/browse/AIRFLOW-4827 ?

[zhongjiajie]

😭 What the matter today. Two PR connect to wrong Jira tickets
Thanks for you remind @OmerJog

[codecov-io]

Codecov Report

Merging #5448 into master will increase coverage by 0.1%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #5448     +/-   ##
=========================================
+ Coverage   79.01%   79.11%   +0.1%     
=========================================
  Files         488      488             
  Lines       30564    30564             
=========================================
+ Hits        24151    24182     +31     
+ Misses       6413     6382     -31

Impacted Files	Coverage Δ
airflow/utils/dag_processing.py	60.27% <0%> (+1.02%)	⬆️
airflow/jobs/scheduler_job.py	70.18% <0%> (+1.24%)	⬆️
airflow/executors/__init__.py	66.66% <0%> (+4.16%)	⬆️
airflow/utils/sqlalchemy.py	80.95% <0%> (+4.76%)	⬆️
airflow/executors/sequential_executor.py	100% <0%> (+52.38%)	⬆️

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[XD-DENG]

Not sure if you have removed wrong test case?
The test case you removed will be skipped if Py version < 3.4, i.e., this test case is the one for Py 3.4+ which should be kept.
(I haven't looked into the test case details. Justing checking the @unittest.skipIf conditions)

[zhongjiajie]

You right, a wrong remove

[zhongjiajie]

CI green, PTAL @XD-DENG thanks.

[XD-DENG]

Thanks @zhongjiajie

[zhongjiajie]

Thanks @XD-DENG