Problem importing "DebugToolbarExtension" with 0.12.1

[creagel]

With version 0.12.1 is not possible to import DebugToolbarExtension from flask_debugtoolbar:
The following import is working with 0.11.0 but generate error with 0.12.1:

from flask_debugtoolbar import DebugToolbarExtension

Result:

from flask_debugtoolbar import DebugToolbarExtension ModuleNotFoundError: No module named 'flask_debugtoolbar'

[jeffwidman]

Thanks, dupe of #168