Update OpenAPI repo path

[aulorbe]

Problem

As described here, the path to the OpenAPI repo has changed. Subsequently, we have to change the path in our justfile.

Solution

Update path in justfile, run just bootstrap to update generated core code and update go.mod and go.sum files.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• 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
• Infrastructure change (CI configs, etc)
• Non-code change (docs, etc)
• None of the above: (explain here)

Test Plan

CI passes.