agl-demo-control-panel: update SRCREV

agl-demo-control-panel: update SRCREV

Update SRCREV to pick up:

31573c8 Enable secure mode in default configuration
617a152 Rework configuration saving
08857a6 Improve vehicle simulator
6b21032 Add ability to disable HVAC and steering wheel pages
f2c7811 Simplify server configuration
ceb0b8b Add gitlab issue/merge request templates

Bug-AGL: SPEC-5138, SPEC-5141, SPEC-5142, SPEC-5143

Change-Id: I762a26ede4162a7b2bac895d38c59ce3d222b69f
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-demo/+/29944
Tested-by: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account