test(manifest): Fix manifests validation

[niheaven]

Description

Skip manifests test since there is no bucket directory in scoop core.

bin\test.ps1 is now an alias to test\bin\test.ps1

How Has This Been Tested?

Before:

After:

Checklist:

• I have read the Contributing Guide.
• I have updated the documentation accordingly.
• I have updated the tests accordingly.

[niheaven]

For Scoop-Bucket.Tests.ps1 file in bucket repos, further investigation is needed.

[rasa]

LGTM (but I haven't tested)

[niheaven]

I'll merge this and may add a Tests bucket in the organization which is used for features testing that use develop branch as its backend. When collaborators tend to add some new features to scoop core, they can add testing manifests in this repo (e.g., testing manifests in #3502).