add a config for Dependabot
add a config for Dependabot

Tell it to check both locations where there are Ruby dependencies
loitering about.

Signed-off-by: Robb Kidd <11cd4f9ba93acb67080ee4dad8d03929f9e64bf2@chef.io>

robbkidd/supermarket,chef/supermarket,robbkidd/supermarket,robbkidd/supermarket,chef/supermarket,chef/supermarket,chef/supermarket,chef/supermarket,robbkidd/supermarket