Unexpected GitHub username prompt when vendoring component with invalid URL

### Describe the Bug

Unexpected GitHub Username Prompt When Vendoring Component With Invalid URL.

### Summary

When running `atmos vendor pull` on a component that contains an invalid GitHub URL, Atmos unexpectedly prompts for a **GitHub username** instead of reporting that the URL is incorrect.

This leads to misleading authentication prompts rather than a clear error indicating that the repository cannot be found.

### Expected Behavior

Report wrong url.

### Steps to Reproduce

Place the following `component.yaml` in ``.
Then, `atmos vendor pull -c `

`component.yaml`:
```yaml
apiVersion: atmos/v1
kind: ComponentVendorConfig
spec:
source:
uri: github.com/cloudposse-terraform-components/aws-ec2-XXX.git//src?ref={{ .Version }}
version: v1.537.0
included_paths:
- "**/**"
excluded_paths: []

### Screenshots

_No response_

### Environment

_No response_

### Additional Context

_No response_