Add strict schema check to OpenAPI Agency Budget parameter

[horatiorosa]

Description

Currently in issue # 400, the acceptance criteria does not require us to set a strict check on the parameter. It would be better to more specific as to what parameter we are expecting, similar to what we have done for the parameters for Community District, City Council District, Borough Id, and BBL.

Acceptance Criteria

• Update the query parameter schema to include pattern: ^[A-Z]{1,2}$ in OpenAPI documentation and ensure kubb is regenerated.