Create dependabot.yml
Create dependabot.yml

Add dependabot dependency check in order to maintain dependencies up-to-date and security updates on time.

Signed-off-by: David Ureba <0533fdec30d2cb9a08d514dae132498421180cf3@aiven.io>

GoogleCloudPlatform/alertmanager,GoogleCloudPlatform/alertmanager,prometheus/alertmanager,GoogleCloudPlatform/alertmanager,prometheus/alertmanager,GoogleCloudPlatform/alertmanager,prometheus/alertmanager,prometheus/alertmanager