layer.conf: move to next release
layer.conf: move to next release

poky master now supports only dunfell, so let's move up by one release.

Signed-off-by: Martin Kelly <c87c89f8a4ed3f9815bf6eb199372979d459c1c8@xevo.com>

intel-iot-devkit/meta-iot-cloud,intel-iot-devkit/meta-iot-cloud,intel-iot-devkit/meta-iot-cloud