protobuf vulnerability

USN-8063-1 fixed a vulnerability in Protocol Buffers. This update provides
the corresponding update for Ubuntu 18.04 LTS and Ubuntu 20.04 LTS.

Original advisory details:

It was discovered that Protocol Buffers incorrectly handled recursion
when the Python google.protobuf.json_format.ParseDict() function is being
used. An attacker could possibly use this issue to cause Protocol Buffers
to consume resources, resulting in a denial of service.