Pixelbin

- Added [upload](./README.mdupload) method.
- Removed support for signature generation for APIs.

- Fixed parameters for `getPresets` method.
- Added support for using a proxy with the Pixelbin SDK by setting the `trust_env` option to `True` in the `httpClientOptions` object of `PixelbinConfig`.
- When `trust_env` is set to `True`, the SDK will trust the environment settings for proxy configuration or the `~/.netrc` file if present.

- **Breaking Change:** Function signature of `sign_url` in `security.py` has been updated. The argument `token_id` has been replaced with `access_key`. Access key for a token can be found by going to console.pixelbin.io > `Settings` > `Tokens` > Click on any Token > `Access Key`.

- Added method for generating V2 Signed Multipart Upload Urls `createSignedUrlV2`

- Fixed regex for Custom Domain URLs

- Added support for generating signed Custom Domain and PixelBin CDN urls