If assert_request_schema_confirm and Committee::Middleware::RequestValidation are used at the same time, date-time validation fails.

Description

If I use Committee::Middleware::RequestValidation, the date-time conversion is done at the same time as the request is processed.
Then, if I run assert_request_schema_confirm, the conversion is already completed and the validation will fail in the following part
https://github.com/ota42y/openapi_parser/blob/v0.12.1/lib/openapi_parser/schema_validators/string_validator.rb#L11
At this time, the value is already converted to DateTime.

Is this a bug?
If you have any solutions, please let me know.

Environment

ruby 2.7.1
rails 6.0.3.2
committee 4.2.0
rspec 3.9.0

application.rb

config.middleware.use Committee::Middleware::RequestValidation, schema_path: schema_path, parse_response_by_content_type: false

OpenAPI 3.0 yaml

/contents:
  get:
    summary: example
    description: example
    parameters:
      - in: query
        name: q
        description: filtering
        required: false
        style: deepObject
        schema:
          type: object
          description: filtering
          properties:
            start_at_gteq:
              type: string
              description: start_at greater than or equal
              format: date-time
              example: "2019-10-01T00:00:00+9:00"
              nullable: true
            end_at_lteq:
              type: string
              description: end_at less than or equal
              format: date-time
              example: "2019-10-31T23:59:59+9:00"
              nullable: true
    responses:
      "200":
        description: contents list
...

spec

it "foo" do
  get contents_url(q: { start_at_gteq: "2020-01-01", end_at_lteq: "2020-01-31" })
  assert_request_schema_confirm
  assert_response_schema_confirm
  expect(response).to have_http_status(:success)
end

spec result

Committee::InvalidRequest: #/.../schema/properties/end_at_lteq expected string, but received DateTime: 2020-01-31T00:00:00+00:00

  0) ContentsController request spec GET #index ...
     Failure/Error: assert_request_schema_confirm

     Committee::InvalidRequest:
       #/.../schema/properties/end_at_lteq expected string, but received DateTime: 2020-01-31T00:00:00+00:00
     # ./spec/spec.rb:98:in `block (6 levels) in <top (required)>'
     # ------------------
     # --- Caused by: ---
     # OpenAPIParser::ValidateError:
     #   #/.../schema/properties/end_at_lteq expected string, but received DateTime: 2020-01-31T00:00:00+00:00
     #   ./spec/spec.rb:98:in `block (6 levels) in <top (required)>'

Start with the reproduction in spec.rb, using Committee::Middleware::RequestValidation and assert_request_schema_confirm together. Read lib/openapi_parser/schema_validators/string_validator.rb at the referenced validation point and trace how the date-time query value becomes DateTime. Done when the request and schema confirmations handle this combination consistently without the reported type error.