[Tests] Add CI test for doc build #13666

Job	Run time
python-test (3.8, tests/unit_tests)	5m 53s
python-test (3.8, tests/test_api.py)	3m 44s
python-test (3.8, tests/test_cli.py)	4m 9s
python-test (3.8, tests/test_config.py)	3m 34s
python-test (3.8, tests/test_global_user_state.py)	3m 43s
python-test (3.8, tests/test_jobs.py)	4m 21s
python-test (3.8, tests/test_list_accelerators.py)	3m 46s
python-test (3.8, tests/test_optimizer_dryruns.py)	5m 26s
python-test (3.8, tests/test_optimizer_random_dag.py)	3m 58s
python-test (3.8, tests/test_storage.py)	3m 28s
python-test (3.8, tests/test_wheels.py)	3m 40s
python-test (3.8, tests/test_spot_serve.py)	3m 56s
python-test (3.8, tests/test_yaml_parser.py)	3m 43s
	53m 21s

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