releng: update versions to 0.3.0Updated for Trace Compass 8.1.0 releaseChange-Id: I470d60b249c52ec135c36896fd92217c3d1020adSigned-off-by: Patrick Tasse <patrick.tasse@gmail.com>Reviewed-on: https://git.eclipse.org/r/c/tracecompass.incubator/org.eclipse.tracecompass.incubator/+/195513Tested-by: Trace Compass Bot <tracecompass-bot@eclipse.org>Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>