run dependabot weekly instead of daily

[kevinjqliu]

Feature Request / Improvement

Currently dependabot runs daily to pick up the latest change. This can be noisy and we dont need the most up to date dependencies. I propose we run it weekly.

Thoughts?

[Fokko]

I don't really mind the noise, but don't have a strong opinion either, I'm okay with both. We can also run it biweekly (Wednesday and Sunday for example).