Allow overriding the font download url

[reda-alaoui]

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• 查找历史相关issue寻求解答
• 翻阅FAQ
• 翻阅PaddleX 文档
• 确认bug是否在新版本里还未修复

描述问题

By default the font download url is hardcoded at

PaddleX/paddlex/utils/fonts.py

Line 97 in 72e5bb8

url=f"https://paddle-model-ecology.bj.bcebos.com/paddlex/PaddleX3.0/fonts/{self._font_name}",

I'd like to replace it with my caching http repository url (Sonatype Nexus).

Would you accept allowing to override it via an environment variable for example?