Fix with using oslo_serialization base64 module

The test_can_create_server_with_max_number_personality_files
Tempest test is expected to use base64 module from oslo
serialization package, but the b64decode() from std Python lib
is called. The current patch fixes it.

Change-Id: Icf23aa128b8f857f98096e86ff945241efa96b9a
Closes-Bug: #1625079
1 file changed