JS client: latest axios version causes type errors

[mvandenburgh]

From the code for the S3FileFieldClient constructor:

/**
   * Create an S3FileFieldClient instance.
   *
   * @param options {S3FileFieldClientOptions} - A Object with all arguments.
   * @param options.baseUrl - The absolute URL to the Django server.
   * @param [options.apiConfig] - An axios configuration to use for Django API requests.
   *                              Can be extracted from an existing axios instance via `.defaults`.
   */

On the latest version of axios, axiosInstance.defaults returns an object of type AxiosDefaults instead of AxiosRequestConfig as it did before. This is a new type introduced in axios/axios@94a9344#diff-7aa4473ede4abd9ec099e87fec67fd57afafaf39e05d493ab4533acc38547eb8L151-R171 that slightly differs from AxiosRequestConfig. Since S3FileFieldClient expects apiConfig to be of type AxiosRequestConfig, using axiosInstance.defaults as the example specifies results in a type error.