python3: convert dbus-unit-test.py
python3: convert dbus-unit-test.py

The latest Ubuntu release (focal) no longer installs a default "python"
in the filesystem. The only issue found converting this script over to
python3 was that splitlines() now returns a bytes string. os.environ did
not like that so explicitly convert the byte string to a normal string.

Change-Id: I05f4c8a8090074c71c9afd156f5963b6f6668884
Signed-off-by: Andrew Geissler <f7919ac9f8ec0c3ffbc3f483da625c634fd31638@yahoo.com>

openbmc/openbmc-build-scripts,openbmc/openbmc-build-scripts