Use latest `oauthenticator` version #210

Job	Run time
build-test-images (jupyterlab, gpu)	3m 48s
build-test-images (jupyterlab, cpu)	4m 16s
build-test-images (jupyterhub, cpu)	1m 58s
build-test-images (dask-worker, gpu)	1m 44s
build-test-images (dask-worker, cpu)	1m 39s
	13m 25s

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