* Added to_data_uri method and path_to_data_uri classmethod for Image class.
* Removed path_to_data_uri classmethod and modified _get_mime_type to use mimetypes.guess_type function instead of hardcoded dictionary.
* Register image/webp with mimetypes before guess_type to support WEBP mimetype detection on Python 3.10.
* Improved branch coverage for Image.to_data_uri.
* Added Image._to_data_uri example in the docs.