[deprecation/fix] correctly automatically get the module in which deprecation utils are called

There was a missmatched combination of:

• the frame wasn't always correctly grabbed
• grabbing the frame in the situation of a decorator didn't make any sens, so switch to func.module
• the tests were bad and expected "[logilab.common]" while it should have been "[test_deprecation]" because it was there that the depreciation was declared