Fix “no signature key” in Ubuntu/Debian

Trying to update an Ubuntu 16.04 but was failing constantly because no signature key was there as you can see from the following warning:

Looking at the error above, apt is telling us that the following keys are missing: 40976EAF437D05B5 and 3B4FE6ACC0B21F32.   Notice that these are listed multiple times. Each unique key will…