chore: Update dependabot schedule to the weekend

[manupedrozo]

Description

Updating dependabot schedule to run on the weekend as agreed internally.

Link to any related issue(s): -

Type of change:

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• This change requires a documentation update
• Documentation fix/enhancement

Closes #[issue number]

Checklist

• I have signed the MongoDB CLA
• I have added tests that prove my fix is effective or that my feature works
• I have added any necessary documentation (if appropriate)
• I have run make fmt and formatted my code

Further comments