Adopt `binderhub` #139

Job	Run time
Build tljh_repo2docker	1m 16s
Build tljh_repo2docker	1m 16s
Integration tests (local)	8m 47s
Integration tests (local)	8m 47s
Unit tests (3.8)	38m 27s
Unit tests (3.8)	38m 27s
Isolated tests	36s
Isolated tests	36s
Integration tests (binderhub)	8m 5s
Integration tests (binderhub)	8m 5s
Unit tests (3.9)	24m 15s
Unit tests (3.9)	36m 5s
Unit tests (3.10)	38m 46s
Unit tests (3.10)	38m 46s
	4h 12m 14s

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