[FEATURE] Add Dependabot configuration for auto-updates

[VachaShah]

Is your feature request related to a problem?

The dependencies in Gemfile might be out of date with newer versions of the gems available. It might be difficult to manually update the dependency versions each time.

What solution would you like?

Add a configuration like Dependabot which can auto-update the dependencies.

What alternatives have you considered?

A clear and concise description of any alternative solutions or features you've considered.

Do you have any additional context?

Done for other clients like https://github.com/opensearch-project/opensearch-java/blob/main/.github/dependabot.yml, https://github.com/opensearch-project/opensearch-js/blob/main/.github/dependabot.yml etc.