16039: Touch python clients so they run tests with the latest SDK.

Otherwise, "pip install" (during "install services/nodemanager", for
example) downgrades the SDK from the current version to the latest
version published on pip, and all test suites run with that version,
instead of the version we think we're testing.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@tomclegg.ca>