Description

This PR adds unit tests for fetching from Git, HTTP, and OCI URLs using ephemeral test servers.

Fixes #179

Miscellaneous

• Extract duplicated test suite setup code into new testutil package (e.g. populating a database backend)
• Embed the BasicAuth struct from go-git into netutil.BasicAuth and remove unnecessary overridden methods. Now created by using the new netutil.NewBasicAuth(username, password string) function
• Replace generic //nolint:revive directives with explicit revive ignores, e.g. //revive:disable:defer

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings