[BUG][GO] Build error if 2 properties have binary format

Created by: krhubert

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

go build produce an error

./api_default.go:113:6: localVarFile redeclared in this block
        previous declaration at ./api_default.go:102:6

Here is the declaration of the variable: https://github.com/OpenAPITools/openapi-generator/blob/08fb59009a8565295b1e091eb0c514b7439245e8/modules/openapi-generator/src/main/resources/go/api.mustache#L236-L239

openapi-generator version

 docker pull openapitools/openapi-generator-cli:latest

https://hub.docker.com/layers/openapitools/openapi-generator-cli/latest/images/sha256-19f983d1a396391e13e1010c8ca0f27577eacb68f83a07fffa778bec40e033ee?context=explore

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: api
  version: 0.0.1

paths:
  /media:
    post:
      requestBody:
        content:
          multipart/form-data:
            schema:
              type: object
              properties:
                image:
                  type: string
                  format: binary
                video:
                  type: string
                  format: binary
      responses:
        200:
          description: Success

Steps to reproduce

docker run --rm -v "${PWD}:/local" openapitools/openapi-generator-cli generate -g go -o /local/out/go -i /local/openapi.yaml

Related issues/PRs

None

Suggest a fix

Change the variable name for every property that has a binary format.