SDK-1739 : Create dependabot yml

[JagadeeshKaricherla-branch]

Description

Add Dependabot to this repo to check and automate dependencies for :

• npm packages
• Github Actions

Type of change : enhancement

Please delete options that are not relevant.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] 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

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code

Mentions:

List the person or team responsible for reviewing proposed changes.

cc @BranchMetrics/saas-sdk-devs for visibility.

[ahmednawar]

@JagadeeshKaricherla-branch Can you add specific people as reviewers? The SDK Dev alias is mostly for cc'ing the team for visibility.