Feature Request: Allow Configurable BASE_DIR Using Environmental Variable

[gknor]

Currently, the BASE_DIR in the code is hardcoded as os.path.expanduser("~/.paddleocr/"). It would be beneficial to allow users to specify the BASE_DIR through an environmental variable, giving them more flexibility in configuring the application.

I propose to make the BASE_DIR configurable through an environmental variable. This change would allow users to set their desired directory path for storing PaddleOCR data.

I would modify the code that sets the BASE_DIR to check for the presence of an environmental variable, say PADDLEOCR_BASE_DIR. If the environmental variable PADDLEOCR_BASE_DIR is present, use its value as the new BASE_DIR. If it's not present, use the default path as os.path.expanduser("~/.paddleocr/").