pm-graph: v5.12, code revamp for python3.12

sleepgraph/bootgraph function correctly in python3.12 but include a slew
of deprecation warnings for unsupported regexes. This patch fixes up all
the strings in the code so that it comforms with python3.12 standards.

Signed-off-by: Todd Brandt <todd.e.brandt@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>