sysutils/py-google-compute-engine: update to 20190416 [1]

This fixes a python3 runtime issue [1]

While here, pull in missing dependency in python3 case [2]

PR: 237505 [1]
PR: 237203 [2]
Submitted by: Lucas Kanashiro <lucas.kanashiro@collabora.com> (maintainer) [1]
Submitted by: Miroslav Lachman <000.fbsd@quip.cz> [2]
Approved by: Lucas Kanashiro <lucas.kanashiro@collabora.com> (maintainer) [2]