function swaggerFileFilter (file) {
  const isSwagger = /^\.(?:json|yaml|yml)$/.test(path.extname(file.Key))
  console.log(`file ${file.Key} is${isSwagger ? '' : ' not'} a swagger file.`)
  return isSwagger
}
Takes in an s3 listObjectsV2 object and returns whether it's a "swagger file" (one ending in .JSON, .YAML, or .YML),
and whether it's in the catalog folder (S3 Key starts with "catalog/").

In the future, this could be extended to look into the file for the swagger version declaration.

@param {Object} file an s3 listObjectsV2 response object
@returns {boolean} whether or not the file is a swagger file (JSON/YAML)