add VerificationProperty

[kosaku-hayashi]

Description

Added VerificationProperty to the Database property. This resolves the following issue when querying items such as Notion Wiki pages.

Fixes #475

Notion Wiki pages are internally treated as databases. When querying Wiki pages, I confirmed that a VerificationProperty is included in the response.

"expiration date":
{
"id": "verification",
"name": "expiration date",
"description": null,
"type": "verification",
"verification": {}
},

Type of change

Please delete options that are not relevant.

• 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

How Has This Been Tested?

The unit test completed successfully and I tested with my Notion integration that Wiki page queries and the search API work properly.

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