removed excessive line (in `TaskManager.add_pilots` method) #206

Job	Run time
test-getting_started / tests	3m 10s
test-tutorials (configuration.ipynb) / tests	2m 3s
test-tutorials (debugging.ipynb) / tests	2m 52s
test-tutorials (describing_tasks.ipynb) / tests	4m 8s
test-tutorials (multiple_pilots.ipynb) / tests	5m 27s
test-tutorials (profiling.ipynb) / tests	3m 1s
test-tutorials (raptor.ipynb) / tests	3m 8s
test-tutorials (staging_data.ipynb) / tests	3m 33s
test-tutorials (submission.ipynb) / tests	1m 37s
	28m 59s

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