This commit applies the Black format to the `dcmanager/db`
files to ensure that it adheres to the Black code style guidelines.
Test Plan:
PASS: Success in stx-distcloud-tox-black
Story: 2011149
Task: 50444
Change-Id: Id6b0e2f15ea7c8ee79b3c35b534bf3a27893256b
Signed-off-by: Hugo Brito <hugo.brito@windriver.com>
9c91fffa07