manifest: update loramac-node to v4.7.0

Update loramac-node to release v4.7.0 from v4.6.0. The `v4.7.0-zephyr`
branch contains the same 4 additional commits as `v4.6.0-zephyr`.

Signed-off-by: Jordan Yates <jordan.yates@data61.csiro.au>
1 file changed