Change update check in dependabot config to weekly
Change update check in dependabot config to weekly

change update frequency to cut down on PR 'noise'.

REF: https://dependabot.com/docs/config-file/#available-schedules
rprouse/html5-boilerplate,h5bp/html5-boilerplate,h5bp/html5-boilerplate,rprouse/html5-boilerplate