[FEATURE] Add Dependabot Security Updates for Go Modules and Weekly Govulncheck Workflow

[dwisiswant0]

Describe your feature request

Add two new features:

1. Dependabot Update: A new security group in the gomod ecosystem focusing on security updates for Go modules.
2. Govulncheck Workflow: A GitHub Action to automatically run govulncheck every week -> uploads the results to GitHub in SARIF format.

Describe the use case of the feature

1. Dependabot Security Updates:

   • Automates critical security patches for Go modules, so we don’t have to worry about them manually (example: stop using deprecated mholt/archiver #5951).

2. Govulncheck Scanning:

   • Finds vulnerabilities early, so we can fix them before they escalate into serious issues.
   • Uploads results directly into GitHub’s security dashboard, making it easy to review and handle problems.

Describe alternatives you've considered

No response

Additional context

The Dependabot change is just for security updates. Both features reduce technical debt: Dependabot handles security updates automatically, and govulncheck ensures our dependencies are secure w/o extra manual effort.