enable Dependabot v2
enable Dependabot v2

https://github.blog/2020-06-01-keep-all-your-packages-up-to-date-with-dependabot/

Fixes #111

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/jimfs/pull/111 from sullis:dependabot-v2 f732c8eb0826432a63cddb0792d769768e8409d2
PiperOrigin-RevId: 336111706

google/jimfs,google/jimfs